My friend Marv was selling some 4x4 mechanical keyboard kits, and I drew up laser-cut acrylic cases for them. The first case is for the original design which used an arduino micro. This turned out to be a difficult-to-track-down MCU, and another friend dvdfreitag has made a new version which uses the much more readily available Pro Micro for the MCU.
Marv posted a build guide for the keyboard. There are two case options in each dwg file. The first is a simple base plate and key alignment grid designed to be used with standoffs and remain open on the sides. The second is a box style case designed to be glued together once everything is working. It can also be used with 10mm standoffs so it can be disassembled for cleaning and maintenance, as long as the top is not glued down. In both cases, the acrylic top plate is used in place of the PCB top plate shown in marv's build guide. This is not technically necessary, but I think it looks better.
The keyboards run on software generated at kbfirmware.com and the 4x4.json file below has the configuration for the 4x4 board's defaults using a 32u4. You can use the site to generate a hex file, and then upload it using the qmk toolbox.