The design is an approximation based on the BP2 by Turn Racing to fit my Turn wheel R320 and the DYI 3D printed TURN racing magnetic shifters (you can find them at https://www.thingiverse.com/thing:5173125).

ALL the holes for the switches and rotaries are 13mm as it fits most of the standard ones you can normally find on amazon. I attached also the CAD files so feel free to change it to your need. Just post a make ;-) - thanks.

For the electronics I had a BBI-32 Button Box Interface with Connectors laying around for years so the interior bay is designed to fit just that.

Top and bottom part Hardware QTY 4 inserts M3 QTY 6 inserts M4 QTY 4 HEX socket cap screws M3x5mm (for the BBI-32 base) QTY 6 HEX button head Screws M4 x 30mm (for the 2 half of the body) QTY 5 HEX Countersunk M5 x 45mm (lenght depends on the quick release)

Knobs for rotary switches (shaft dia. 6.5mm) QTY 3 grub screws M4 (they work even without if the fit is right)

PS: the same is posted at https://www.printables.com/model/531188-button-plate-r320

Update 2023-08-11 Button Plate Top with all holes 12.5mm added illuminated buttons https://www.aliexpress.com/item/1005002612117502.html?spm=a2g0o.order_list.order_list_main.6.6e7b1802SI24wb