Simply system for non permanent mounting of photos to 5mm thick foamboard.  Take the guide, and using a cheap hole punch (mines from Harbour Freight) punch the desired holes into the corners of the board.

Punch 9/64th (3.5-4mm) holes. The outer two are used by the edge clips.  These have a small allowance  so you can adjust the photo to pull it taught.  The inner one can be used for 3x2mm magnets; the post goes into the board and the photo is held in place by magnets on the front side.