This is a larger frame than the original to make it possible to scan 645 to 6x7 frames. It is also a bit oversized as I like to scan the film margins. I added some blocks to add soft material for film cleaning. There are also slots for expansion attachments. The STL is scaled a bit to account for 0.25mm tolerance. The 135 mask is not so convenient as the dedicated one as the slot on one side does not extend all the way out. But if you scan strips there's no problem.