If you look in the metric fastener drawers at any Home Depot you should find what you need. For the foam pad, just cut a closed cell foam flotation toy crosswise, drill a hole in the center (I'd use the bit by hand) and glue a center-drilled dowel that fits over the motor shaft eliminating the coupling. Is the shaft recessed on both sides of the round?
The coupling that came with my dryer cracked on day one. I made one to replace it in 5 mins.
If you find the right material rigid foam you could drill undersize and use a snug fit, there is no real torsion introduced by the drying process.