Key Wallet

This key holder requires two bolts and two nuts to hold it together, plus washers to fill the space between the two halves if there are not enough keys.
Edit to warn: the key wallet broke after a month for no apparent reason. I guess the ABS plastic did not stand the repeated small-amplitude flexing in the pocket. Sharp points of the ABS when it breaks are also annoying. I recommend more rubbery/flexible material.