Warning about pvc is good - I feel like sterner caution about leather might be warranted - e.g. veg tan leather is fine (if stinky) but most leather you see is gonna be chrome tanned and lasering it will blast heavy metal vapour / toxic dust into the air and contaminate your enclosure.

IMHO if you are a beginner you should be very careful about cutting any material that hasn't been explicitly designed to be laser safe.