This is a simple case that I made for my KK2.1 board. It may fit other KK boards Like the 2.1.5 This case doesn't fit the 2.0 at this time. If there is enough interest I may mod it to fit the 2.0 also.
First thing I would say is that this case needs to be printed nicely so that it snaps together. I printed this on a flashforge creator X Pro at .2mm layer height in ABS. If your printer is not tuned as nicely as my printer you may have to scale the upper case a little to get it to fit. Once snapped in place it is easiest to open by prying it apart with a knife.
When you assemble it I would put foam tape or servo tape on the board to act as cushioning spacers on the board. Then I use servo tape or foam tape to attach the case to your quadcopter.