Long fiber injection (LFI) is a process in which the polyurethane resin system and the crushed fiberglass roving are sprayed into an open mold. Variable (usually low) compression pressure is then used to create complex parts in multiple variety of sizes.
The main advantages of the LFI are: short completion cycle times, minimal waste and the creation of a rigid, resistant, durable and very resistant material to deformation and breakage, possibility of in-mold painting, or with thermoplastic skin, in this case. ‘last case with an aesthetic effect (homogeneity, brilliance, duration) far superior to the normal painting.

Structural reaction injection molding (SRIM) is one of the two best variants of the reaction injection molding (RIM) process. While the other more common variant, Reinforced Reaction Injection Molding (RRIM) focuses primarily on increasing the strength and size of the resulting products, SRIM instead focuses on increasing stiffness.

Like RRIM, SRIM reinforces the printed part through the use of glass or carbon fibers. However, while RRIM uses milled or cut short fibers, SRIM relies on fiberglass mats or meshes, which are traditionally placed in the mold prior to resin injection.