[fock]

While I don't play Badminton (and so can't test with a racket on hand) this seems very cool! I also thought about something similar for judging bikewheel spoke tension - I guess I have to research this a bit more now.

As for monetization: I personally don't have problems with static ads served from your domain. Find some celebrity or brand and ask them if they want to have you serve their banner.

[zhacker]

if spokes come in standard guages, it should work for bikewheels as well. There may be some differences due to the bike rim material, but in case of badminton, I found out that frame material could be ignored safely.