Photopolymers are a class of thermosets that polymerised after light exposure: the photochemical reactions start and the formation of the polymer network leads to mechanical and chemical modification of the final material. Cationic photopolymerization is a powerful and efficient method for photocuring the liquid resin and to obtain the thermosetting polymer with excellent characteristics: an important class of cationic photocurable monomers is the epoxy-based one. In the polymeric additive manufacturing sector, the photopolymers still represent the most employed material: in particular the stereolithography (SLA) process, which ensures the highest spatial resolution and object definition, takes advantage of liquid photopolymers solidified through the interaction with laser light emission, that starts the photocuring reaction of the resin.