No, I did not repaint the case. It was a low cost restoration, basically.
Citric acid for rust/paint removal on the plates, black anti rust coating from a spray can afterwards.
The foam is a 2mm EPDM sheet. Bought it at a small german webshop that specializes in stuff like that... your best bet might be to just search on ebay. It's how I found mine, too. I've heard Neoprene is fine as well.
For the holes, 10 and 2mm leather working hole punch tools are a huge help.