The wonderful technicians working in NASA’s machine shop at Lone Star made some parts for us allowing us to improve the design of our robot.
How do we account for these parts in our BOM? The materials were donated by one of many teams so we would have to guess at a cost for them. Do we treat it as if we paid an outside (non-sponsor) machine shop to make the parts or is NASA considered an overall sponsor?
You will need to account for the “fair market value” cost of the materials on the Bill of Materials. Do your best to find the cost of the raw materials from a “vendor” and use that price in the Bill of Materials. (This is what you would do for any donated materials – the fact that you received them from another team at a tournament does not affect their accounting on the Bill of Materials.)
Items made by the machine shop at tournaments are counted as “team” labor and do not need to be accounted for as if they were paid.
So, for example, if the parts you had made by the machine shop were some motor mount plates cut out of a 12" x 12" by 1/4" thick aluminum plate, then you could look up the prices for the raw materials at online suppliers such as onlinemetals.com or mcmaster.com and use those prices in your Bill of Materials.
However, don’t just take my word for this, read the official rule R16 in this year’s robot rules. I think the second-to-last example in the blue box under R16 is the one most similar to your case, as the machine shop at a tournament is most similar to the “recognized sponsor of the team” situation (although in this specific case, they are a “recognized sponsor of the event” where the team is participating.)