This is a wall patch I made for a big ole' hole I had in my wall. This covers it up and fits my industrial decor. It's surprising how little “industrial” or “ship compartment” decorations are available, so I figured I'd start making it myself. Here's the initial result. 

This is made to be finished with Modern Masters Iron Rust paint. This special paint goes on black, then you apply a rust accelerator and literally within 10-15 minutes, the surface is covered in real rust and this plate looks exactly like a metal patch that was quickly placed over a hole in a bulkhead or wall.

You can print this with anything you want. PLA is pretty easy to paint and it's cheap, so that's what I used.