I have a mini CNC controller to show off this week (tomorrow at build club). This runs basic gcode off an SD card. It has a little display and a few nice features, like pausing, resume and feed rate override. It does have a few issues and the Chinese documentation was pretty rough.
If you are looking for a simple way to remove your PC connection, this might be for you. The size is about 160mm x 100mm.
I have it hooked up to my Bridgie machine to demo.