Step 3: Start the assembly
Once you jam this metal piece in, you will want to get the magnet ready for insertion. To do this, cut another piece of thin steel that is approximately the same size as the magnet. Make it square with round corners for ease of insertion. Smooth to edges and corners as previous. See pic.
Once you have the smaller steel sheet cut and smoothed, place your magnet on it and eyeball where you will need to cut the innertube to allow the magnet clip to hold your hard-earned cash. Leave a little (about 1/2" ) of extra innertube so that you can glue the innertube closed so that the magnet doesn't espace. See pics.
Once you have the innertube cut, then clean and scuff the opposing surfaces of the tube as it you were patching a tire. Use the scuffing tool provided in a typical bicycle patch kit. Insert the magnet on the metal piece. The key is to have the metal piece you inserted into the main body of the wallet to interact directly with the metal piece you cut for the magnet. The metal backing of the magnet is typically non-magnetic, so you will want the two steel pieces to touch, through the innertube to hold your cash while minimizing the magnetic field present at your credit cards. You will know if you have too much magnetic field at your cards if they stop working. You have been warned. I personally have had no problems.