This is a MOSFET board mount for my Monoprice Maker Select v2.1. It's similar to the one linked as a remix, but it was created from the ground up. The main feature is the standoff holes have threads for M3x6mm screws, which you should have a ton of if you've done the Z-brace mod.
I made the bottom solid so that you can use velcro or double-stick tape to adhere it to the inside of the case.
MOSFET Board is available here:
https://reprapchampion.com/collections/electronics/products/3d-printer-heated-bed-power-module