I was asked to put feet on the bottom of a bag I am making for someone. It's a Bow Tuck, of which I can make in my sleep by now! I bought this pack of 4 discs at Joann's that have a metal washer (like with magnetic snaps) and longer very flimsy arms to splay out. Question is, did I get the right feet and how do I attach them? I figure I need to go through the lining and outside of the bag, but not sure. Please help! I do put in a firm bottom, but I make a slip cover for it and just put in inside on top of the lining so it can be taken out and washed, not sandwiched between lining and outside. HELP!