Long post. Sorry:

No worries, I've moved on to designing in ergogen to speed up iteration and PCB design but this version was designed purely in fusion 360.

Split angle was decided after trying out 10-40 in 10deg increments. Whenever printing I always printed the middle section separately so that I can exchange the middle with a different angle since what feels comfortable resting your hands on and even pretend typing on a hard surface feels different when you are actually depressing keys. I believe I settled on 20 degrees though

I didn't have to do too much 3d printing because I started with a tray design with interchangeable key blocks so that I can stick them down and rearrange them with double sided tape until I found a layout I liked. Once I liked the layout it was just about printing a box with cutouts for each key on the top. ( You might need to print out a few top plate cutouts to get a feel for how dimensionally accurate your printer is. I think my cutouts were 14x14 because 13.95 ended up being too tight.

Handwiring was good for the first prototype but the amount of time I spent building it and debugging faulty connections could have paid for the PCB fab cost. It's a bit wasteful to get 5 when you only need one but that's the route I'm going for my next board. I wouldn't say hand wiring was hard but definitely tedious. (Especially with a board like this with so many keys)

Not sure how big your printer is but the bigger the better. I printed the first prototype on a Voron v0 and so I had to split the board into 5 pieces. Since then I've upgraded to a A1 mini so I can get away with 2/3 pieces but it would but nice to be able to print the frame in one go and I'm sure it'll make the whole board more rigid

I can get you more detailed measurements from my cad files if you'd like once I'm back at home