The present disclosure is drawn to material sets for 3-dimensional printing, 3-dimensional printing systems, and 3-dimensional printed parts. A material set can include a thermoplastic polymer powder having an average particle size from 20 μm to 100 μm, an x-ray contrast ink including a jettable x-ray contrast agent, and a fusing ink. The fusing ink can include a fusing agent capable of absorbing electromagnetic radiation to produce heat.