It took awhile to get everything to work together properly! I designed and made this on my CUBE 3D printer: there are 3 parts to make. The bolt is hollow and it will hold a rolled up piece of American currency. The cap nut is reverse threaded so most people will never even know it can be opened to reveal the secret surprise (money) inside! The design on the cap nut (two intersecting dollar signs) is there to remind you that this bolt can be disassembled and may hold some money so you do not accidentally throw it away!. Have fun.