Basics

This Page Aims to Lay Out The Existing Methods of Post-Processing 3D Printed Things
It also will organize methods that need further investigation

Existing Methods

Pretty straightforward
Needle Files , Deburring Tools , and Sandpaper rest is self explanitory
- Also maybe a Microfiber Cloth / "bath" in the sink or a Parts Washing Bin to clean off any Microplastics / burnt bits
A Hot Air Gun / SMD Electronics Rework Station can be used for small details like Stringing related "fuzz" ~~or just a Butane Lighter if you are desperate~~
Main Downside is Time Spent

Also known as "Sandblasting"
Media Blasting is the more broad concept, and especially given the hardness of (most) FDM 3D Printed Plastics, a less "aggressive" media is most likely required
Would need to look into the existing literature on all this
In theory could something like Plastic Pellets / Plastic Regrind be used?

This only works for certain plastics, but a Solvent (Typically Water or Acetone ) is vaporized in a chamber, the print is placed in there, and the vapor (partially) dissolves the surface of the material
After a certain time period of exposure, the part (or the solvent if done in some fancy Solvent Recovery method, Vacuum + Bakeout ?) is removed
- The solvent then evaporates leaving behind a smoothed (but sometimes deformed, reducing/predicting and accounting for this is key) surface
(akin to Recrystalization / Zone Melting removing impurities, it does the same but for surface finish impurities)
Main Downside is Solvent Cost (especially if Solvent Recovery (short of "don't dump the bucket down the drain until all of it was used/evaporated") isn't done) and the potential for part deformation)

Given they are Thermoplastics , FDM 3D Prints Can Be Either Re-melted, or Simply Heated Up
This allows layer lines to "blur" and the part fuse into a single stronger one, or it can simply work in a manner similar to Post-Weld Heat Treatment
In order to prevent part deformation/drooping etc this is typically done in some sort of media
CNC Kitchen et al have documented using Plaster and Table Salt (Check if Iodonized Salt or just straight up Sodium Chloride (Although Did it also contain Anticaking Agents ...) )
It needs to be studied, but if something along the lines of Chopped Glass Fiber / Chopped Carbon Fiber were used (or to an extent maybe just Carbon Black ), could something akin to Case Hardening be achieved?