The default switch width/length is 18mm to fit inside standard Cherry MX key switch cutouts (in a top plate) but you can shrink that down to probably 14mm (just

The default switch width/length is 18mm to fit inside standard Cherry MX key switch cutouts (in a top plate) but you can shrink that down to probably 14mm (just change the parameters in the .scad). Alternatively, you could just cut a sheath-shaped hole in the top plate where you want the switches to go and then you wouldn't even need a switch body and could cram the switches really close together. I used a trick like that with this silly fidget toy I made a while back: https://gfycat.com/calculatingthankfulgoldeneye https://gfycat.com/calculatingthankfulgoldeneye