What sort of device is available to hold the Ilford 3 1/2 x 3 1/2 inch multigrade filters on an Omega D2? I've been holding them with my fingers, but I'd prefer to have a holder of some sort. B+H has some kind of filter holder for the D2, but its dimensions / compatibility aren't mentioned.

Also, can I use a red #29 filter as a safe filter for positioning the paper?