Now modified, test fit and printed over my 6plus.
Requires rotating before printing (one day i'll figure out how to rotate the .stl) and the eyepiece needs support - see my pic for a working method.
Screen images are simulated, its night time and I didn't fancy pointing my rifle out the window to get a scope pic :)
Apologies for anyone who downloaded the original model to find the fit was less than great.
if you need a different diameter eyepiece - leave a comment and ill upload one to suit based from the Outside Diameter you give
Wanted a way to use my iPhone's camera to look through my spotter scope so I don't have to move once taking my shot at the paper target. The design was inspired by whiteboardwarriors2's design for an iPhone 4s. I guess it could also be mounted directly to a telescopic rifle scope; but unless it's an air rifle or .22 rimfire, I wouldn't recommend it due to recoil.
The case part was intended to also accommodate a thin (1.2mm extra) case all the way around. But should hold a case-less phone in much the same level (for the lens centre) as the genuine cases don't wrap around the bottom.
Also has access for a charger should your battery start getting low.
Print one of the cases out on its back and an eyepiece to match the outside diameter of your scope's eyepiece then push together to assemble with a blob of your favourite sticky stuff. There is a little bit of extra room inside the cup to be as gentle as possible on your scope, but feel free to plastidip as whiteboardwarriors2 did on theirs i remixed from. Nice idea.
There is a little notch on the back of the eye-cup to help locate the cup to the case on 55mm cups+. In some cases - glue may not be necessary. Also complies with Apple's recommended "keep-out" zone for the field of view on the lens; taken from their official drawings.