Post-processing refers to working on the print after it has already been printed. We do not mean support and brim removal, but rather acetone vapor finishing, combining large prints, and even painting.
Smoothing the Surface Quality
There are a couple of ways to improve the surface quality of a print after printed. Since ABS is soluable in acetone, if the part is made of ABS, or some form of ABS combination, you will be able to give it an acetone vapor bath. This will allow the part to become more water tight and give it a shine that is similar to injection molded pieces.
PLA can be smoothed with a brush on gel such as XTC. This is a bit more time consuming and less effective than an acetone vapor bath.
To properly apply an acetone vapor bath, it is easiest to have a slow cooker and a vacuum. You can do an overnight acetone vapor bath at room temperature, but results have been much better in a slow cooker. It can take a little while to hone in the amount of time required, but when done correctly, parts should only take around 2 minutes to give a good acetone vapor finish. Once that is complete, it is best to vacuum purge the parts to remove any excess internal acetone and improve strength.
One annoying thing about printing can be the size limitations of the build area. The largest standard FDM printers for sale are right around 1 foot3. That doesn’t mean you can’t split larger prints up and combine them after printing. ABS can be welded with ABS cement and PLA can be combined with strong super glue. Cracks can then be filled with a 3D printing pen to increase strength. Once strong, the seams can be smoothed out with bondo or spackle. Once the entire part is strong and the cracks are smoothed out, most materials work great with spray paint.