Use Algorithms to Create Bespoke Sewing Patterns
By Poppy Mosbacher. Posted
This article was originally published as part of HackSpace magazine, which has since been incorporated into Raspberry Pi Official Magazine.

Spurred on by the lack of patterns available for tall men, Joost De Cock (who is 6’6”) started Freesewing.org to solve a personal need.
"I wanted to alter patterns to fit me but as a novice it’s not always easy to know what to do. So I bought a book to learn how to draft my own patterns based on my own measurements. But it’s slow and boring drafting by hand," explains Joost.
With a job in IT and a passion for sewing, he was well placed to come up with a digital solution. “I thought it must be possible to automate the process. It all started as something to scratch an itch.”
The site now has 12,000 users with a colourful showcase page displaying photos of appreciative people wearing the clothes they’ve made.
To get started, you’ll need an account where you add your measurements. Then pick a design and the software will automatically create a bespoke pattern for your body shape. There’s a range of patterns to choose from, including a suit jacket, hooded jumper and shirt. For Cosplay fans there’s even a Sherlock Holmes style coat.
The majority of the patterns are for menswear but there are a few unisex and womenswear clothes. “At first I put the effort into making the patterns I needed. Designing womenswear is on the to-do list, now more people are using the site,” says Joost. "Version 2.1 will include 3 new patterns, 1 uni-sex and 2 womenswear. It should be out by the end of this week. Just to underscore that we're serious about womenswear."
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True to its name, Freesewing is free to use and completely open source. The patterns are coded in JavaScript and there’s a step by step guide that walks you through the process of creating your own pattern from scratch. Even if you’re not a coder, it’s interesting to have a look at the guide because it shows how the algorithms work. The code for the patterns, platform and website are all available on GitHub.
Joost says the main challenge to the project is “maintainer burnout”, so when people donate it’s a great morale boost. But he’s not doing it for the money and pays all the expenses out of his own pocket because he realises he is in a “privileged” position “with a good job and a roof over my head”.
All the money raised through the site is given to the charity Médecins Sans Frontières (Doctors without Borders). “It makes this project socially responsible as well as fun to do. And I need that to convince myself it’s ok to spend all my time doing this, because each year, I get to write a cheque to people who need it so much more.”
To find out more about Freesewing and to get involved, visit freesewing.org

Poppy is a maker and writer. She loves getting tech into the hands of people who do traditional crafts. She is helping set up a makerspace in Devon and was a director of BuildBrighton makerspace.
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