Filter holder 8.9x8.9 cm for use in the Krokus 4sl (round) photo enlarger. The filters I designed the holder for are Foma Varian Filters (8.9x8.9), but should work with others.

It consists of 2 parts - the holder itself and the pressure cover. The lid slides into the recess with some force, you may want to print the lid a bit scaled down (I sandpapered mine a bit).

For printing I recommend to use black matte filament, so that it is not transparent and does not make unnecessary over-reflections / color changes of the photo enlarger lamp.