I've read somewhere that it can be skuffed with a 3M pad or sanded dull.

A method I haven't tried yet is to take torn scraps of tissue paper wetted with glue and water and make a semi tough skin over the foam.

I've tried low temp iron on directly over foam and it never turns out very good....even though it might look OK right after it's done, it doesn't take long to deteriorate.

One thing I should make that would make sanding foam less of a mess is a vacuum table. That would encourage me to do more foam projects.