If there is a local mine or quarry you might hit them up. They use heavy rubber belts for material movement. I got a piece for free. 8' x 36" little heavy but doesn't move.
Tractor Supply carries a horse stall matting that works well. You can get a piece cut to fit, 4×10× 3/8 thick. Got ours for around $40 .
I did this and used rubber cement to attach a pitching plate and then painted a stripe on it. Use indoors and out so far this year it's held up well.
Tractor Supply carries a horse stall matting that works well. You can get a piece cut to fit, 4×10× 3/8 thick. Got ours for around $40 .