After realizing that the best camera I owned was on my phone, I set out to provide it with a telephoto lens ahead of my trip to Alaska. So I measured the dimensions of the phone in its case, the location of the camera lens, and the diameter of the eyepiece on my binoculars.Though an STL is provided, it is unlikely to be a match to your phone and binoculars/telescope. Download the OpenSCAD file and adjust the (documented) parameters to your needs.