I finished up a quick project the other day, and thought I would share. I made this dragon door knocker for my mother. It was 3D printed based on the files located on thingiverse here. The author of the files included a link for finishing techniques on instructables here. I started out following the instructions linked, but ran into an issue that I will describe farther down.
Immediately after printing there was a lot of support material that needed to be scraped off in order to finish the print (the support material is added automatically by the software I use with the 3D printer, it allows the printer to make the overhanging pieces which would otherwise simply collapse). I scraped and sanded off as much as I could see and then put a coat of primer on the piece. It is hard to see fine details before painting the natural PLA because it is translucent. Once I had a coat of primer applied, I scraped off the remaining support material, and used a dremel to smooth it out. It is a bit hard to tell in the picture above, but there was still a lot of material to clean up.
The instructable then recommends using XTC-3D to smooth out the print and make it stronger. This worked really well, and I will probably use it in the future. There was some loss of detail due to the coating, but the smoothing effect was very successful.
The instrcuctable also recommended applying iron powder to the print, and then using ammonium chloride to oxidize it, which would give it a neat aged effect. Unfortunately, I bought the wrong kind of iron dust, which did not oxidize at all. Bummer. So I painted it instead.
The XTC-3D mixed with iron powder dried to a matte black color (the color of the powder), which I painted over in Rustoleum "Flat Soft Iron".
I then sprayed Rustoleum "Metallic Rust" onto a paper towel, rubbed it lightly over the high points, leaving the "Flat Soft Iron" to show through in the crevices.
Finally, I dry brushed gold over the highest points on the piece to provide stronger contrast overall and make the scales pop a little better. One really neat thing about this print is that the support material was set up so that it would hold up the knocker while printing, but once it was removed, the piece would move freely overall. This allowed knocker to have moving pieces, but print out as a single solid unit.
