I recently purchased a Chrosziel CMB-ST mattebox that has a 142.5mm opening, and it came with a rubber bellows that covers to 110mm. As it turns out, I want to use Zeiss super 16 lenses that have an 80mm opening. I have looked around and the adapters are either costly or back ordered.
Does anyone have any cheaper solutions for covering the opening to prevent light leaks? Any leads would be greatly appreciated.