I printed with D2 enlargers for years in a commercial lab. We always used the large (6" x 6" ?) CP filters inside the door above the condenser. Above the condenser there is little concern about scuffing and dust, and the filters do not have to be gelatin, just the cheaper CP filters. If you're going to be doing color at all, invest in the Omega color head, oor in the Minolta additive electronic head. The Besseler color heads are not as good. ---john.