I have a Silhouette, that is the same thing as a Cricut.
All you need is a 3-10 amp power supply like 9v battery or an old battery charger,
q-tips and a salt-vinegar-water. I think we did a Fireside Chat show on etching that had how to do serial numbers. I'll make you enough stencils for you to practice with.
Just tell me what you need and the size like, to fit PF940___ or PF9ss
I can get the size from stuff I all ready built or give me a sive you need.
I'll cut you a set of four serial numbers more if you think you might need them and I'll mail them to you.