Nylon 12 (PA12) is the powder almost every SLS project starts with. Parts come out grey and matte, with 50 MPa tensile strength and a modulus of 1850 MPa, so they are stiff without being brittle. They absorb little water (0.66% per ASTM D570), so their dimensions do not change noticeably with humidity.
It is currently the only material we also print on the Fuse X1, where we can make single-piece parts up to 330 × 330 × 565 mm or hundreds of small parts in a single build. On the Fuse 1+ 30W we use it for small and medium parts with fine detail.
Choose PA12 when the part has to hold precise dimensions and carry moderate loads, as with housings, brackets, clamps or assembly parts. If the part has to bend a lot or take impacts, PA11 has more than 3 times the elongation at break (40% against 11%). If you need more stiffness, or the part sits under load at high temperature, look at PA12 GF.
Under a light load of 0.45 MPa, PA12 holds up to 171 °C (HDT). At 1.8 MPa the limit drops to 87 °C, so it is not suitable for brackets mounted next to an engine.