I had a hole in my screen door that the kids kept making bigger. This was supposed to be temporary, as I wanted to make more fun shapes (hearts, squares, triangles, etc), but this ended up staying longer than I expected. Used M3 bolts and matching square nuts. I believe I used 4mm bolts since I have found little use for them. I should have printed in black, but I got lazy and used the filament that I had last printed with. 

The last image is just light shining through the thin layer of filament. 

I used PETG and no supports. Regular print settings. Nothing special. Enjoy.