Iam not sure right now, but did u try building the blocks as map entity, then setting its transparent flag ? Some time ago this worked ( for water blocks fex ).

greets

Acknex umgibt uns...zwischen Dir, mir, dem Stein dort...
"Hey Griswold ... where u gonna put a tree that big ?"
1998 i married my loved wife ... Sheeva from Mortal Kombat, not Evil-Lyn as might have been expected
rayp.flags |= UNTOUCHABLE;