Bolt with secret compartment

thingiverse

Need to conceal something? This M27 bolt is your best bet - no one will ask questions when they see you carrying one in your backpack. Want a more discreet option? I can drill a small hole into it and turn it into a keychain, making it a comfortable accessory to have on hand. Whether you want to scale up or down, the walls of this bolt are fully adjustable - just be careful not to make them too thick or too thin.