Distributing items which were jointly purchased

I am participating in a technical project at my university which will be funded by the project's team members equally. The money collected will be used to buy parts and equipment for the project. During the project's duration, the remaining money will be kept reserved for use in case a part breaks and needs replacement.

After the project is over, the parts used in the project and the money will be equally distributed to the team members.

The parts distributed will be used, and may be worn. On what basis can the parts be distributed to the team members? Should they be distributed based on their value when they were bought, or should we estimate their current market value?