Currently at the bike co-op where I work and the other one where I volunteer we try to track what parts people are using on their bikes so that when they are done we're not forgetting to charge them for something.

Both co-ops use clipboards with small "receipts" on them for participants/volunteers to write down what parts they've used. The clipboards stay at the front of the shop and are then handed to the person as they walk in. In what I would say is the vast majority of cases these clipboards either don't get used at all or people don't write down the parts on them as they get the parts. I don't think this actually results in that many parts not getting paid for because people are pretty honest when you ask them what parts they used or the volunteer helping them remembers. There are probably small parts like v-brake noodles that get missed though.

The only alternative I've thought of so far is having something permanently attached to where the people are working on their bikes.

Curious if other co-ops out there have a better system for tracking parts people have used on their bikes.

Thanks, David