i dont think theres a set way to do it. An excel spreadsheet is probably the easiest.
Don't worry with exact numbers on unlimited items. Just take a good guess and put a +- next to it to indicate its not exact. I don't think there gonna sit there and count.
If there is something that your only allowed a limited amount make sure you count carefully and put the exact number. If the number is close to the limit, missing, or obviously wrong they probably will check (such as if you claim you used 1 victor in the entire robot).
I don't have the rules in front of me so I could have made a mistake... but i believe this information is accurate.