Rather than heating and melting plastic filaments fed from spools like desktop fused deposition modeling (FDM) machines such as the Replicator or Micro, the Formlabs machines work by directing a laser across a tank of liquid photopolymer resin using a system of precision mirrors. The resin solidifies in thin layers and the model is built up out of the tank. While developing the Form 1+, the company is reported to have looked at every part of the 3D printer to improve performance and reliability.