I've made some improvements on the original pi workbench and I think you'll all be pleased. This version puts the raspberry pi inside, provides active cooling via a 40mm fan, a power switch via 1/4 inch rod, a mount for an LM2596, a rear cover and drive tray. The drive tray slides in and the attached rear cover clips in place via the ridges created by the 3d printer. The internal mount is only useful for an LM2596, which is not enough for a pi 4b. You'll have to use a different dc/dc converter or just power it externally. The coupler is to connect a 1/4 inch rod to the power button on the USB hub. The deck has holes to clip any arduino that matches the mega/uno profile to the box. Just snap on and off. Be sure to use paper or plastic washers with the screws on your arduino. I found out the hard way you can break traces without them.
Use an 8" ribbon extension cable to expose the pi headers outside the box. It's a bit difficult to put in place but you only need to do it once. The drive tray/rear cover will lock the connector in place.
While I designed this for a pi 4b, you can use any SBC compatible with the raspberry pi model B form factor, like a rock64.
Modify it all you want, modify, but don't sell this. If you do share this or a modified version, please cite your original source.