I recently finished up another 3D printed spotting scope/phone adapter. I made it in two pieces and bonded them together with plastic JB weld. The tabs/slots are to ensure alignment. I made one for a different phone last year and it was a PITA using super glue and trying to line up the edges. I did modify the model so all I have to do is type in the dimensions, convert the file and print. I make these so they slide over the cover and are held in place by friction. It's simple, strong and weighs almost nothing. Fun stuff.