LED CupHolder Rings

I am planning to start the LED CupHolder Rings project (just for fun right now) and can someone tell me what's the inside diameter for moomba boat. I was planning to cut 3 3/4 and 3 5/8 inside diameter and add 1/2" to it.I haven't set the selling price (or even calculated my cost) and was wondering how much is the reasonable price you guys think should be. I don't want to spend time if most of the consumer thinks it's an expensive.

I'm planning to use 1/4" or 6mm sheet for that.