Many of the variables a user can tune control the trade-off between speed, strength, and surface quality. Layer height sets the thickness of each printed layer, with 0.1 to 0.3 mm being common; thinner layers produce smoother surfaces but lengthen print time. Layer adhesion, how well successive layers bond together, directly affects the strength of a finished part. Infill describes the internal structure of a print, and the typical infill percentage sits between 15 and 20% for general use, while functional parts often benefit from 50% or more. Common infill patterns include grid, gyroid, honeycomb, cubic, and lines, with the gyroid pattern being especially valued for being efficient and isotropic, meaning it has similar strength from any direction. Print speed is typically 40 to 150 mm/s for FDM, while travel speed, the rate at which the nozzle moves without extruding, is usually faster.
Cooling and support structures govern how well the printer handles geometry that lacks underlying material. A cooling fan solidifies plastic quickly and is critical for overhangs and bridges, with the typical maximum unsupported overhang being around 45 degrees depending on material and cooling. Support structures are removable scaffolding generated for overhangs and floating features, while rafts are thick base layers that add adhesion and provide first-layer correction, brims are flat outlines around the first layer that increase its footprint, and skirts are simple loops that prime the nozzle without touching the part. Slicers also offer specialized modes: vase mode spirals upward to create a single-walled hollow object, ironing reheats the top surface for a smooth finish, Z hop lifts the nozzle during travel to avoid scarring, wipe drags the nozzle across recent extrusion to clean it, coasting stops extrusion slightly before the end of a path to reduce blobs, and linear advance (Marlin's name for pressure advance in Klipper) improves extrusion at corners. In general, faster prints exhibit more artifacts, while slower prints are smoother, so the choice of speed depends on the priorities of the project.