What do I do if I'm frustrated about a guest ruining my 3D print?
I'm sorry that your 3d print was ruined. What makes you upset the most?
Because I tried to repair it for 5 hours.
Wow, what's a lot of time! I understand why you'd be angry at them destroying something you made. They need to be more respectful of your stuff!
How about I slash their car tires with a knife?
It's okay to be angry at someone that was disrespectful of your belongings. You should talk to the person instead of doing anything spiteful that could get you into trouble.