Filter tray adapters to allow use of common 3 and 4" sized filters in the non-standard 150mm filter trays on matte boxes that came with 35mm Konvas and Kinor cameras. They are designed to hold Tiffen glass filters, which are generally up to ~4mm in thickness. As is usual with Soviet-era camera gear, not every filter tray is manufactured in the same way; these adapters fit perfect in some of my filter trays, and are loose/tight in others. You may need to tweak the source to fit your specific unit. Designed with FreeCAD. Source files available on Github: https://github.com/fdiebel/filter-tray-150mmI printed with PLA filament on the following settings, and results were great. Print two of these for each filter tray.