I got a MyRetroComputer https://myretrocomputer.com/ case/keyboard and wanted to install a MiSTer FPGA in it.

These are inserts to add a sturdy backpanel for USB, HDMI, etc and USB on the side. I also wanted a somewhat authentic power switch, so I ordered a Commodore-style power switch on eBay.

I printed the backpanel with supports. The top of the case kind of hooks into it to hold it in place, but the bottom-right corner is a bit loose. Overall though it's sturdy enough for plugging and unplugging USB and HDMI cables. Use panel mount extension cables.

I printed the sidepanel without supports. I didn't have a PCB to solder the power switch in to. Basically I soldered a DC power jack and connector to it to plug it into the MiSTer/DE-10 Nano, and designed a bracket that screws together to hold the switch into place. It screws in where the original flash memory expansion was located.

Power switch: "New Commodore C64/C128 1581 replacement power switch" at https://www.ebay.com/itm/402027981537

Even though I installed a MiSTer/DE10-nano in this case, these inserts aren't specific to it and if you have a solution for mounting a Raspberry Pi these should work just fine.

I installed a MiSTer FPGA (DE10-Nano) and usb hub using this: https://www.prusaprinters.org/prints/75977-mister-fpga-and-usb-mini-itx