I didn't really use a "pattern", but copied the belt loop used for some 1911 mag holders I had. I made my badge holder from a couple of pieces of thin (probably 4 oz.) leather. I used one piece to wrap around the belt, and another piece to frame the badge. It is held looped around the belt with a couple of chicago screws. I punched a couple of holes in the loop for the pin to go through. I also put a dab of hot glue on my pin closure latch to keep it in place.
I wear the badge on my shotgun belt. As Lynyrd Skynyrd said...Nuthin Fancy....