this belt buckle it the offspring of old diamond plate and some well deserved time in my shop. it is a very common shape and one of the better clothing articles i own.
Step 1: Things to gather
motorized wire brush
rubber mallet or hammer
blow torch and solder
dremel tool (optional)
ball pean hammer or mallet
3x4 inch piece of diamond plate aluminium
belt new or old it doesn't matter
Step 2: Basic layout
all off the planing should be done on the back of the plate just to make is easy.
once the you have the pattern drawn you can begin cutting out the buckle. you can use a hacksaw or another tool i used my dremel with a small cutting disk so i could better follow the curves dont worry if you dont get the cut too close because you need to better round the edges with the bench grinder to get the correct profile.