Have your design parametrically generated for you. Belt, bearings, export STL to print, and assemble with hardware.
The model still needs some debugging, and set space for mounting hardware.
I didn't make this a more collaborative design, because I wasn't sure l could actually contribute anything. There are juggernauts of talent, having years of specialized training or 30 years of experience (or both) in a field, which is awesome but intimidating. I am pleased with how it turned out, but I don't imagine that it can't be vastly improved, so an obvious comment to you might make a huge difference to me and this project. As well, I am an example that anyone can contribute to this project so please do, join and contribute.
The model is not finished. I am going to break out specific posts in the coming days, specifically on the design of the tooth gears and the center wave generator. What is known so far, what are the trade offs, and what can be worked on in the future, keep up to date with this project if it interests you.
Link to the model you can also search public documents for 'strain wave gear' and copy from there. https://cad.onshape.com/documents/589ec3b62ec4e50f8780f313/w/e3bc2d0aadf1fac7a95c44f8/e/b461997c4947a96f94b88547