I occasionally make circuits for various projects. I find the Sparkfun PRT-12070
to be an excellent board to build projects on. It has the same wiring as a standard breadboard, making it easy wire up a standard IC or module, with some external parts. This clip also works with the Gikfun GK1007
version of the same board.
Mounting this board can be a pain. You need 4 screws, carefully located, and a set of appropriate spacers.
This clip makes mounting the board easy. The clip mounts with one screw, and the protoboard clips in.
Details: The clip's mounting hole is 0.15" or 3.8mm. This size works well with a #6 machine screw. The clip is designed with 0.25" or 6.3mm of clearance on the underside of the board. The top of the board is about 0.5" or 13mm above the surface the clip is mounted on.