I made a bumper for an arduino single relay module in order to protect the pins from possible shortcuts, something very dangerous working with AC. It also makes the module look nicer :) Althought in the picture it may be not apreciated, the board fits very tigh in the bumper, so it won't fall from it. This is my first design and I made it with OpenSCAD.   The bumper counts with holes so you can screw it in case you want. If you want me to make any modification or to release the source file, just post a comment. Right now the code is a bit messy but I will clean and upload it if someone wants it.