Who wants to mess with cutters and cardboard when you have a 3D printer. This case is designed to take a lens (from a dollar store binocular). The lens had a focal length of 75mm. The holes fit 38mm lens from a cheap dollor store binocular, I used the mount from the binocular itself, just yanked it out so it fits snugly in the holes. This is more for a concept as its unlikely you will find the same binocular or have a Nexus 5 in the exact same case as I do. Kids had a lot of fun.Print, drop lenses on one end, the phone on the other. Enjoy.