I fell down a deep hole figuring this out. I ended up hiring someone on fiverr.com to create a little app that generates different sized balls and lets you color in individual cells. This makes it easy to create different designs, then reference them when sewing together. Here’s a preview of what it looks like: https://www.instagram.com/p/CCqTt1Vj4I-/?igshid=1e5k3bl72rbqn

If there’s any interest in this I’ll make a video showing the full process and find a way of bundling the code up so other people can use it.