There are a bunch of excellent deck boxes already available for Keyforge, but I wanted to make one as slim as possible, which was also robust and transparent enough to see the deck inside (with the right filament).
To do this, I used the Vase Mode/Spiralize function to create a single walled case the precise size for my sleeves, with a friction-fit lid.
I have both Dragon Shield and Ultra Pro sleeves, so created files for both of these. The Ultra Pro box is smaller due to the smaller/thinner sleeves.
There isn't much margin for error in these deck boxes, so you might need to tweak your settings for your own printer and materials. I had to experiment a lot to find the right balance between fit/slimness/sturdiness, and I've included the settings that worked for me below.
I would strongly recommend using PETG for these boxes, as I found that when printed with PLA the bottom would often break, whereas the PETG versions are very sturdy.
These are the print settings that worked best for me.
Spiralize [Cura]: Enabled
Nozzle Size: 0.5mm
Layer Height: 0.2mm
Line Width [Body]: 0.9mm (can be thinner but the walls start to flex)
Line Width [Top]: 0.6 - 0.7mm (depending on preferred tightness of friction fit)
Bottom Thickness: 1 - 2mm (depending on preferred sturdiness of base)