I used cardboard as the back for my ath-tape strop, I'm thinking though that the oil base would dissolve the tape glue, leaving you with an expensive mess. I've seen pics on other forums, and the Lee Valley website of diamond on MDF so it seems to work, the diamonds embed themselves into the top layer I guess. you could also try just the MDF that stuff is pretty abrasive. MDF by manufacture is very consistent, so it should lap and stay fairly flat. YMMV