As far as I can tell this is the only Win 3 Mini PC case available on the internet as of the end of 2023. If someone thinks they can make a better case, please do so, and send me the link afterwards so I can use it myself.

This is not a beginner project. There is a high chance of destroying your Win 3 if you don't know what you're doing. This model requires an accurate 3D printer to fit the USB ports and audio jack, but i suppose you could probably scale it up a couple percent in the slicer to account for a looser printer (not tested).

You will need a USB C hub with Power Delivery and display out to use this. Even with the display cable removed, the device still thinks it's attached, so in the Windows display settings set “Show only on 2” and set your resolution to whatever you want. Also make sure “display 2” is set as your main display.

Vague Directions:

Win 3 disassembly is fairly straightforward. You'll have to remove the fan and heatsink to get the board out, and then re-attach them once the mainboard is free. The device will boot without the battery, thankfully, that was my main concern when starting this project.

The wifi antennas can be disconnected during initial disassembly, but you will have to de-solder them from the Win 3 housing in order to transplant them to the mini PC case. It's a simple process with a soldering iron and a bit of flux. You could likely just snip them out near the end, but that will negatively affect your wireless performance.

Print the case halves in the obvious orientation where the large flat area is on the bottom.

The bottom case will need a bit of gentle stretching to get the Win 3 board into position.  I put the USB A side in first, then carefully bend the other walls as needed to slip the board into place. Just be careful not to strain the board and it'll be fine. I made the case tight like this so I wouldn't need any screws or fasteners to hold the board in place.

Don't forget to re-attach your Wifi and Bluetooth antennas after the board is fitted into the bottom case. The black cable goes into the antenna slot labeled “Main” and the grey longer cable goes in “Aux”. I would put a glob of hot glue or a piece of tape over the exposed metal ends of the wifi antennas to prevent them from shorting the board. On the model you'll see a fixture to help route the long antenna around the inside of the case.

PLA is good enough with typical print settings, and I've designed the openings and standoffs in a way to keep all the hot components away from the plastic. However, this has only been tested in a room temperature environment. If you're looking to put this mini PC in a hot car or outdoor location it will likely melt, so use PETG if that's your plan.

This build mostly uses parts from the GPD Win 3 and a 3D printer, the only other thing you need is a hot glue gun or sturdy tape for mounting the power switch and securing the case halves together. I used hot glue, but electrical tape is probably a better idea that is less permanent.

The power button is attached last. You'll need to use that tape or hot glue to secure the power button cable in a way that keeps it from being ripped out of the board. You'll see a hole in the case for the power ribbon cable, and you can use a toothpick or plastic spudger to set the clamp on the power cable after the case has been assembled.

Random Unnecessary Reading:

Win 3's with broken control sticks are about $350 on eBay. That's a pretty good price considering the power and included display. But I feel like most people attempting this project will already have a Win 3 collecting dust.

The power button uses a small 4 pin connector to attach to the board. If you destroy the power button that comes with the Win 3, I think one of the "Switch Lite Flex Cable On/Off Button Ribbon Power Cable" from Aliexpress might work as a replacement power button, but I havent ordered one yet. If you know a good alternative to the power button please let me know.

It would be fairly simple to remix this model to allow for mounting the Win 3 display and speakers, but I'm kinda burnt out on this project for now, so I'll let the next guy do that one. If you do make something like that, please show it to me when finished.

Lastly, it would be way easier to just remove the battery and run the original case as a mini PC.