FDM (Fused Deposition Modeling) or FFF (Fused Filament Fabrication) 3D printing is the most widely spread and affordable 3D printing method.

FDM 3D printers work by melting plastic and layering it down with a heated nozzle as the build plate moves down by the desired layer height which usually is 0.2mm but most printers can go even finer than that often having layer heights down to 0.02mm.

This technology is good for fast prototypes which prefer strength and cost efficiency over the overall look of the part for example stand alone gear mechanisms.

SLA (Stereo-Lithography Apparatus) 3D printing is the first and oldest method of 3D printing,

Although it may be the oldest it is the most precise affordable (relatively) 3D printing technology so far. It uses a powerful UV laser to cure special UV curable resin in the form of a desired object. The laser dot is only 0.07mm thick which allows for very fine and intricate details. After a layer is printed the build plate moves up by usually 0.1mm and the next layer is printed, the layer height can be as small 0.005mm on some printers.

This printing technology is mostly suitable for models where high quality is desired, such as D&D miniatures, I had a lot of orders for those and everyone was more than happy with the quality.