Features

Two Sizes. Which can be easily adjusted if a different length required

Inward or Outward Pull for easy adjusting when on your body

Detailed instructions to help you make a hip belt that will fit most backpacks that have an attachment point.

Seamless finish. Different finishing techniques described to have a professional finish

Great scrap fabric project to use up leftovers from your backpack project 🙂

Printable PDF Pattern and Full Instructions

US Letter, A4 and A0 paper sizes

Every step is illustrated and described for complete clarity. No confusing wall of text or half-baked video like you can find elsewhere.

Sew your own commercial quality gear with beginner friendly instructions.

Not for commercial use.

FREE/Donate What You Want at PayHip

Features

15 Litre Capacity. The main body is approximately 12 litre with 3 litres of additional pocket volume. Volume is calculated from fabric modelling software for accuracy.

Vest Style Shoulder Straps that hug your body for a secure and comfortable fit. Lace up straps for fine tuning the fit, with instructions for alternative attachment methods.

Several pockets for organisation and easy access to your essentials.

• 6 pockets on the shoulder straps
• Large external stash pocket (for coat, wind breaker etc), designed to be accessed on the go.
• Top zippered pocket for small items such as a phone, sunscreen etc

Hydration Bladder Sleeve on the back panel to ensure optimal hydration, with suggested instructions for internal hydration storage.

Four Point Compression on each side to ensure the bag can be cinched tight to minimise bounce.

Zip-Up Main Compartment because when you want to move fast, the faff of a roll top and top buckle strap won’t cut it.

Stretch Stash Pocket for windbreaker and rain shells on the go.

Printable PDF Pattern and Full Instructions

Includes US Letter, A4 and A0 paper sizes

Every step is illustrated and described for complete clarity. No confusing wall of text like you can find elsewhere.

The guide goes out of it’s way to not only include the most comprehensive instructions, we also include a free 25 page beginner sewing ebook to get you started.

Sew your own commercial quality backpack with beginner friendly instructions.

Not for commercial use.

£7.99 via Payhip

Also on Etsy

Price may include a digital tax if applicable in your country

Show off your builds!

Use the contact links at the top and bottom of the page.

@pricklygorse Instagram and Facebook

Handstand canes are a great way to try something new with your handstand training. They are a little bit easier to balance on because you can move them under you. They promote trying harder to not fall, let you try new moves (presses, negatives, crocodile transfers etc) and the most important one, just look cool to show off on.

I wanted a set that has adjustable width so I can make them wider for doing dip exercises as well as handstands in the narrower position. They can also be disassembled to fit inside a 20L bike pannier (just about).

These were made from a 2.4 metre length of 6 x 1 (15cm x 1cm) planed wood. Apologies, we mix and match units in the UK, especially with DIY…..

The blocks for the hands are 3.5 x 5 x 2 inch

The blocks are attached to the base via 1 inch wide threaded pipe and 2 flanges for each cane. I have used 30cm long pipe.

Block spacings: I like to have my hands about 38cm apart, which is roughly my shoulder width. These canes can go from 35.5 to 50 cm apart. Beginners might want them a bit wider but as the shoulders get stronger and more flexible you should aim to bring them closer towards shoulder width for better handstand alignment. Wider is easier for bend arm pressing however.

Alternative Adjustable Base

An older version I just used a 60cm wide base piece and drilled multiple holes. This works well, but doesn’t fit in a pannier or most backpacks. With the canes on the outermost widest hole spacings it works well for dips, but isn’t quite as stable when trying one arm stuff because there isn’t much lateral support. A 75 cm wide base would have likely been a better choice. As mentioned above, I like my blocks about 38cm apart, so I recommend hole spacings that go from around 35 to 50 cm wide to accommodate a wide variety of people.

You may have already seen my article on how to pattern bags with darted corners, but if would rather just have the work done for you. I’ve got you covered with this pattern generator! Just input the dimensions and options you would like, and click generate!

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Want to support development of more free tools?

Please donate via Paypal or Ko-fi or purchase a random pattern from this website

These free tools take up a significant amount of my limited personal time so any support is appreciated 🙂

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This produces a mathematically correct pattern for the dimensions you provide, which is more accurate for rounded corners than the approximation I described in the darted patterns article. A pattern for the base to optionally sew the darted panel to is also generated.

Note! There might be bugs, so test your patterns on scrap paper or fabric before committing to the expensive stuff. This is a work in progress project.

Any issues, use the socials or contact me link above to let me know.

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Latest Articles and Tools

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  Online Darted Pattern Generator

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  Draw and Automatically Generate Sewing Patterns For Free Online

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  Circular Bag Pattern Generator

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  Bag Volume Estimation

]]> /online-darted-pattern-generator/feed/ 0 6995 /online-automatic-pattern-generator/ /online-automatic-pattern-generator/#respond Fri, 11 Oct 2024 11:36:17 +0000 /?p=6551

Not sure how to start making patterns? Do you struggle with the maths of calculating accurate middle (gusset) pieces. This is the tool for you!

I have previously released a Inkscape extension that can automatically generate patterns from shapes drawn, such as bag side panels. Not everyone has access to or uses Inkscape, so I’m working on bringing that key functionality to an online tool. Nearly instant patterns for backpacks, bike bags (frame bags, top tube bags etc) and more.

Work in progress! Might have some bugs. Test with a paper model or scrap fabric before committing to your expensive materials.

---

Want to support development of more free tools?

These free tools take up a significant amount of my limited personal time so any support is appreciated 🙂

Please donate via Paypal or Ko-fi or purchase a random pattern from this website

---

Start Drawing!

Instructions:

Draw your shape by clicking or tapping on the canvas.

Add gusset split points. Where you want a split/new pattern piece in the gusset (perimeter side loop), tap an existing point. Split points are shown with red markers.

Delete points by clicking any red split point.

Move points by clicking/tapping and dragging any point

Add new points on lines by tapping/clicking anywhere along a line segment

Add seam allowance by pressing enter or click the Finish Shape/Add Seam allowance button to complete the shape. A helpful 3D view also appears! You can adjust the seam allowance in the pattern generation options

Scaling is adjusted by either specifying the actual real world dimensions of each grid square, or choosing a line segment and specifying the known length of that segment

Background image for tracing is added by clicking the browse button, and opacity can be adjusted. If the background image has wonky perspective, please use my free perspective correction tool before tracing. No images are uploaded to me, this all runs locally on your device.

Pattern Generation: Specify how wide you want the bag to be (use the 3D view to visualise) and the seam allowance, then click Generate Pattern (or type P).

You will now have a automatically generated pattern, ready to cut out and sew!

Printing and Assembling:

Patterns must be printed at 100% or “Actual Size” or equivalent in your printer settings. Use the scale box to check your printout before cutting fabric.

Cut along the borders and tape the borders together.

Made something cool? I’d love to see. Feel free to share your creations via the social links at the top of the page, reddit.com/r/myog or the contact form.

Known Quirks:

• You can draw whatever, but doesn’t mean you can sew it. For example, patterns with sharp inwards corners you will struggle to sew. Again, test on scraps before fully committing.
• Might have bugs. Test whatever you generate with a paper model or scrap fabric before committing to fabric.
• Linear segments only currently. I might look into curved corners and beziers in the future. For now, just draw lots of points to simulate curves, and move the points if you need to adjust them. Your sewing accuracy will be less than the points not being a perfect curve.
• Wide gussets (wider than the paper width) aren’t tiled.

Sewing Instructions

For general instructions related to frame bags, which are a perfect example of what this tool can be used for, see this article:

A Rough Guide to Custom Frame Bags

Changelog:

14 Feb 2025: Any attached background image can now be optionally included in exported PDF

30 Jan 2025: Volume shown in 3D view area. Slight UI styling adjustments

23 Jan 2025: Workflow Change!

• All point editing functionality is now possible before adding the seam allowance. Functions the same on mobile and desktop, with clicking a point to add, then again to make a split point, then again to delete. No right click needed anymore.
• Clearer scale box on first page instead of text dimensions

For this article we are going to simplify this problem by assuming a 3D rectangle – a cuboid or rectangular prism. More complicated shapes will take further consideration.

The first step most people take is using the fabric panel dimensions, and doing the simple

width * height * depth

calculation. This is great for calculating the volume of a rigid object, but bags are soft and therefore deform. This curvature greatly changes the actual volume a bag can contain.

TL/DR: Its complicated, and don’t stress it too much. It is difficult to compare to commercial products

Pattern Pieces to Finished Bag Volume

Assuming a simple cube or rectangular cuboid shape, using the measurements of your fabric panels multiplied to get the volume is a simple way to estimate. However, bulging and deformation result in a different actual volume.

The idea that a bag has a different volume when filled compared to the fabric dimensions may seem a bit of an odd concept, because the surface area does not change, and the fabric essentially does not stretch.

Take the example on the left on this image, the flat square (e.g a teabag or sandwich bag). Doing the fundamental width * height * depth calculation would result in it having zero volume as it has no depth (just two identical flat pieces of fabric sewn together). However, when it is filled, it clearly bulges out and has volume. For a constant surface area (no material stretching), a sphere is the shape with the maximum volume, so your bag trends towards this. The seams do not allow it to form a true sphere, so you end up with the familiar pillow case shape.

With the tea bag example, the relative volume change from flat to inflated is dramatically large. With a cuboid shape, the relative change is still significant but not as dramatic.

So how can you estimate the volume based on the dimensions of your pattern pieces?

After running many fabric volume inflation simulations in Blender for a variety of common bag shapes (flat pouches, backpacks, bike frame bags), I’ve come to some very generalised rules:

If your bag is cuboid shaped (cube, 3D rectangular, rectangular prism), multiple the width * height * depth of the fabric panels to get the geometric volume then multiply by 1.2 to get a more accurate estimation of the volume when bulged out.

If interested, this is similar to the the mathematical solution for the maximum volume of a inflated 1x1x1 cube is which is approximately 1.2 (Pak and Schlenker 2009). My estimate of the 1.2 multiplier comes from inflating a variety of non-cube shapes which vary from slightly flat to rectangular, approximating typical backpack dimensions.

For flatter pancake shaped bags, multiply by 1.5 to 2 for a rough estimate (yes, volume really does increase a lot for flatter bags, as shown in the above simulated photo).

My bike frame bag is a flat shape (shallow depth relative to length and width), and has a volume of 3.8 litre if you just calculate the geometrical volume of a triangular prism. But running a fabric simulation to inflate it results in a filled volume of 6.1 litre (1.6 times larger). The narrower the bag, the larger the factor (approaching the tea bag problem). The tension from attaching it to the frame will however, reduce this filled volume a little.

And flat bags (flat zip pouches etc) you can use a paper bag problem solution to calculate the maximum filled volume:

where w is width and h is height in metres, and V is volume in m³

If interested, the mathematical solution for the maximum volume of a 1×1 teabag is 0.19 (Pak and Schlenker 2009)

An Alternative Method: Cylinders

Another method for estimating the volume of a filled cuboid/rectangular prism shape is assuming the bag will barrel out when filled to form a cylindrical shape.

The backpack in the photo takes a more cylindrical shape than rectangular cuboid when filled up causing all the panels bulge out.

This will usually be an overestimate. The bag may have stiffeners in the panels, be pressed against the users back which flattens it slightly, or have seams that don’t allow it to fully form a cylinder.

So Which Method?

So far we have just used the width, height and depth of the fabric panels and have calculated 3 different volumes for the same bag! Which highlights that it is difficult to compare volumes between manufacturers because how do you know how they have measured it? For your own projects, use something between the ideal cuboid (width x height x depth) and the cylinder. You could use the average of the two, or the cuboid * 1.2 which is roughly calculated from fabric simulations.

As a real world example, I have a commercially made backpack quoted at 25L, which is a very convenient rectangular cuboid shape. Measuring the fabric panels width x height x length gives a volume of 19L. Assuming a cylinder by calculating the circumference from the fabric panel widths and depths gives 26L (the same as calculating the elliptical cylinder from the filled bag dimensions as explained below). A 3D software fabric simulation with a low internal pressure gives 24L. Taking an average between the width x height x depth and the cylinder will get your own estimates in the right ballpark.

A final way of calculating the volume: If you are familiar with the 3D modelling software Blender, simulating volume is easy by adding a “Simple” subdivision surface multiplier then cloth physics, which is how I generated the above simulations.

Calculating Volume from a Made and Filled Bag

For the inverse problem, trying to calculate the volume of a made bag (cuboid shaped e.g. a backpack), again it is best to avoid doing a simple width * height * depth calculation of your actual fabric pieces as this does not account for bulging.

Instead, you can use the equation for calculating the volume of a elliptic cylinder using the actual puffed out bag dimensions, not the fabric panels width and height themselves.

Or alternatively, use the circumference of the bag calculated from the fabric panel widths in the calculator previously on this page, which will give a very similar number to the elliptical cylinder.

Dimensions

Similarly if you want a bag to fit within a set range of dimensions (such as carry-on airline luggage) you need to account for bulging, and scale down your pattern pieces. The shallower and more pancake shaped your bag is, the more the depth dimension will change when the bag is filled.

A cuboid shaped bag, I’d reduce the dimensions by around 5 to 10% to factor bulging. This is a very rough value.

Flatter bags (the sandwich bag is an extreme example) may require more height removing from the pattern if there are space restrictions. A less extreme example but relevant to MYOG is a bike triangle frame bag. It is a flat shape relative to the length and height, usually about 6cm wide. There is restricted room between the legs for it to fit, and my 5cm wide bag as patterned is currently bulged out to 11cm (and the actual filled volume is 30% higher than if I had done a simplistic volume of triangle calculation). You have to pattern these bags to be far narrower than the actual space it has to fit.

Final Thoughts

Don’t get too hooked up on the exact volume value you calculate! Use this advice to get a ballpark estimate and run with that.

As this article has shown, it is difficult to calculate yourself, and nearly impossible to compare to commercial bags as there is no way to know how the company has measured their products. They might have used small balls of known volume, might have measured fabric panels, might have run fabric simulations, might have assumed a cylinder, might have not even accounted for roll tops correctly etc.

Want to support development of more free tools? Feel free to donate via Paypal or Ko-fi or purchase a random pattern from this website 🙂

Have you ever tried taking a photo of your pattern pieces and tracing them in software, and the dimensions are not quite right? Or wanted to correct the perspective of scanned documents, technical drawings, anything else? This tool will help you correct the perspective of your photo to assist making accurate traces digitally, for example in Inkscape or Adobe Illustrator. Only corrects flat 2D perspective such as paper, not 3D objects.

Might have bugs, let me know!

For best results photograph your object on a grid, or on a object with 90 degree corners with known dimensions.

• Add 4 points to your image in the following clockwise order: top left, top right, bottom right, bottom left.
• Try and make the rectangle as big as possible for the highest accuracy. You can click and drag the points after the rectangle is drawn.
• Specify the known width and height of what you have selected. The units are dimensionless.
  For example, so if you have placed the object on a grid, count the grid squares. If the object is on a A4 piece of landscape paper, you could place your points around the paper and use 290 x 210 as your aspect width and height.
• Click Apply Correction
• Save, then load your image into Inkscape, Illustrator etc and scale to the actual dimensions, and trace!

Double check measurements before applying. The calculation can do some crazy computationally heavy distortions if you make mistakes, or if the rectangle you draw is too small to be accurate, which might cause the script to hang for a period of time.

Changelog

7 Mar 2025: Big update for accuracy

• Added an alignment grid, enabled as default, that moves in real time when you move your points to significantly aid with alignment across the image
• Mobile touch compatible
• Points can now be adjusted and fine tuned by going back after applying correction. I implemented this way because the distortion calculation is too intensive to do in real time as you move the points on the corrected image.
• If you load another image with the exact same dimensions as the previous, the previous points are displayed, to help people who are doing batch runs of very similar images.
• The points are now clear and the cursor hidden when moving for greater accuracy

Previous changelog not recorded 🙁

Any bugs let me know!

Features

15 Litre Capacity. Volume is calculated from fabric modelling software for accuracy.

Low Profile Shape to keep out of your way during activities

Simple Design. A perfect building block to add the features you need

Great First Backpack Project. Learn to sew zips and curved panels.

Front Panel Opening with long zip for easy access to the full bag contents.

Gentle S Shaped Straps.Simple, reliable shape and design. For fully featured straps with pockets see one of my thru hiking pack or trail running pack sewing guides

Printable PDF Pattern and Full Instructions

US Letter, A4 and A0 paper sizes

Every step is illustrated and described for complete clarity. No confusing wall of text or half-baked video like you can find elsewhere.

Sew your own commercial quality gear with beginner friendly instructions.

Not for commercial use.

FREE/Donate What You Want at PayHip

£2.99 on Etsy (includes 25 page beginner sewing ebook)

Show off your hard work!

Instagram @pricklygorse #pricklygorse

Facebook @pricklygorse

Or feel free to send me photos via the contact links at the top of the page!

Suggested Fabrics and Hardware (Notions)

This is to give a rough estimate for budgeting. The sewing guide provides a complete comprehensive shopping and cutting list and should be used over this.

Links to example fabrics at RipstopByTheRoll provided (USA). I earn a tiny amount of coffee money at no cost to yourself to support more free patterns. See my page on recommended myog suppliers for alternative suppliers