Lev Kalman

Hi, I work at a teaching facility where we have six Arri-S kits with matte boxes. We've been able to maintain all the equipment for a very long time, but one thing we're running out of and can't seem to find are the trays that hold the 2 x 2" filters. We're down to one per matte box, instead of the two they can hold. Does anyone know where I can obtain more? Or is there a relatively sturdy DIY replacement? Could a holder be 3-D printed? Thanks for any advice! Lev