a allen,

I'd suggest you contact one of the following vendors who are quite knowledgeable about tapes, foils, magnetic materials and would be able to make a recommendation as to which might withstand outdoor requirements. My first thought would be the magnetic material which can be both engraved and cut with your laser.

Judy Rasmussen mailto:judy@innotape.com
Mike Fruciani http:\\www.laserbits.com