I recently broke the glass on the back of my Google Pixel 3 XL.
I didn't like any of the 3d printed cases, as I found them too bulky for my liking.

So I designed my own.

This case is designed to cover most of the back of the phone (covering up all of the cracked glass I have), but it tries to expose as much of the original rounded edges as possible in order not to mess with the overall feel of the phone.

This "case" was designed to be printed in PLA, as it "clips" to the back of the phone. You might be able to print it in ABS or PETG, however, I haven't tried those materials. TPU will not likely work as I don't think the case would stay on the phone.

Print instructions

I would recommend using 0.2mm layers, as there is a sacrificial layer built into the model, which means that this design is support free.

If you want to print at a different layer height (some of the fillets would likely feel a little bit better), you are more than welcome to download the fusion 360 source file and modify it yourself :)