I want to do some fun keyboard builds and showcase some nice desk setups. Artisan keycaps are realy expensive though. Since I have a bunch of cute LEGO bricks and minifigures, I designed a few LEGO compatible keycaps.
Specification
The first step in the process was to get measurements for keycaps and bricks.
Most 1 unit square keycaps have a width around 18mm. Manufacturers will offer different keycap profiles, so for the height and the stem sizes, I refered to the keyboard switch maker, Cherry. The stem should be at least 3.8mm, so any keycap taller than that should work.
The closest LEGO piece is a 2x2 brick at 15.8mm. With a height of 9.6mm, studs 8mm appart, each with a diameter of 4.8mm and a height of 1.8mm.
While designing keycaps, I've adjusted those numbers as I found that the filament used (PLA or PETG) made a difference on grip.
Designs
Skewed keycap
Block keycap
Double keycap
Download
I oversized the studs from 4.8mm to 5mm diameter and from 1.8mm to 2mm height to achieve a good connection. This fitting might be different for you depending on filament and printer.
If you're going to sell or distribute those, please attribute to me.