IF you've seen 3d prints by some of the current generation of FDM printers (makerbot reprap etc) the results are a little bumpy because of the way the material is layed down layer by layer extruded like toothpaste from a tube surfaces of models retain a bumpy look.
Commercial 3d printers have had a way to solve this problem for quite a while a special solvent is used to dissolve just enough of the bumpy surface to smooth it out and produce smooth accurate models. However like much of the technology behind 3d printing it's patented up the ying yang and low cost hobbyist printers can use it.
Some enterprising chaps have found another way to achieve the same thing using acetone a jar and a heating element you put your model in the jar with a bit of acetone heat the base so the acetone vaporises it is heavier than air so forms a cloud in the jar and disolves the surface of the model making is smooth as glass. Now it's still early days for this procedure it's not yet sure what effects this will have on the models structurally or dimensionally but I'm sure it will likely be a regular part of 3d printing soon with the software adapting models to suit with extra surface layers designed to ablative so the smoothed result is the correct size and shape.
Patents are proving to be a stumbling block for the home 3d printing community the current set of machines only exist because the original FDM patent expire most other forms of printing are still locked down (see the recent law suit that was aimed at shutting down formlabs laser based resin printer) there are all manner of patent that control things like enclosed heated build areas, dissolveable support material, colour printing, loading filament into a cartridge, and all sorts. It's good to see people innovating around these limits.