While I have several Xacto knives and one set, I prefer to use a utility knife for most of my cutting. My typical cuts are with stryene and occasionally dense cardboard (not like the stuff that boxes are made off - this stuff is rigid - I use it for internal bracing of my styrene walls). I found an Xacto not strong enough as the blade seemed to bend. But a utility knife gives a nice clean, and SAFE , cut.
I only use an Xacto on things like clear, thin, styrene (for windows), paper, and other products that are THIN.
- walt