Dude, that are really simple shape. Get some thick cardboard, trace both parts on it and cut it out. To get some sturdiness you have to repeart this part a couple of times until you have enought cardboard-parts to glue them together on a stack. Then try if it "clicks" or not. So.... Most people buy those. You can try to do it in cardboard, but remember that this interlock buckles costs under a dollar.

>>539717
cheers man, If I could just buy one I would, but the thing I need it for has to be made entirely from card or foamboard. thanks for your input