Filter drawer.. What adapters are needed?

[MylesGibson]

I use an Altair Starwave 102 ED-R and I image with a DSLR camera. I use a 0.7x field flattener like this one (not exact model as I couldn't find it):

So it connects directly onto the DSLR, and I can screw my 2" filters into an insert just inside the opening. 

I managed to get hold of a second hand, unbranded 2" filter drawer but I don't know how to connect it into the image train. Both sides of the drawer don't fit into anything, so does anyone know what additional connectors I need?

I can add pictures of the filter drawer if needed. I just want to make changing filters easier!

Edited April 13, 2021 by MylesGibson