Hi Jason, I have built 2 of the fly babys. I drilled 1/8" holes in the corners of the plywood motor mount,lined it up over the foam firewall and drilled 1/8"holes in the foam. I used 1/8" dowels to epoxy thru the mount and 2" into the foam.then epoxy your mount to the foam and dowels.This gives you a lot more holding power over just butting the mount to the foam. Jerry