Staples Office Supplies Stores (USA) sells oversize mouse/desk pads that can be used to replace the dirt/ lint/ humidity collecting - or worn-out felt-backed hard tabla covers.
Tear off the felt, glue the hard cover with contact cement onto the pad and cut the circle out with a sharp razor knife using the cover edge as a guide. The large pads will accomodate enough material for new covers for two tablas and a baya.
