I have done a bunch of battery mods using the 4 battery holder, I cut 1 section out to make it a 3 holder. But you do have to remove a lot of plastic in the battery compartment. Also have added a pack film back to a Polaroid 110A, but sold it. That camera and a Nikon F4 that I sold was a sad mistake on my part. Doing a 150 now, same camera body but not near as good a lens.