Use these platforms with Kensington ErgoSoft Wrist Rests. You'll need to press in 4x 1/4-20 nuts and add some bolts of your preferred length.

I use these platforms with my Keebio Sinc split keyboard. They allow me to match the tenting, tilt, and height. Infinitely adjustable and easy to print. These would go well with any split keyboard: lily58, ergodox, redox, kinesis, ultimate hacking keyboard, dactyl manuform...

I'm currently printing in PETG, so I used some supports for the hexagonal holes the nuts go in. PLA probably won't need any support.