I need a 3D designer

I have a boat that I'm wanting to mount a couple speakers to near the front seating area. The surface is concaved so I need 2 rings that can match that concave/curve to a flat surface to mount the speaker to. The speakers are 7" inner diameter and 8.5" outer diameter the thickest part of the ring shouldn't be more then 1" thick after I cut a hole. I have no idea if the photos are helpfull but let me know if theres a better way to measure it.