Was commissioned to make pieces to convert a boot into Mercury Black's shotgun boots from RWBY. The plating at the front I made from EVA foam, but to save time and effort, I modelled and printed the shells around his ankles and the gun mechanism around the back of the boot.
All come with thin gaps to slip 1inch webbing through. Add some plastic buckles/clips and you have a boot attachment. I went with 4 shells on each side of the foot (8 shells per foot).
There aren't very many pictures of the firing part of the boot. I based it largely on fan art and what other cosplayers had done before. I've taken some artistic licence with the design. The shotgun part is asymmetrical, so you'd need to flip it to get a mirrored one for the other boot.
Shells are very tall and need rafting to hold them in place. Many times on my printer, they would still fall, so I cheated by fixing the edges of the brim to the bed with hot glue which I later picked off.