Hi @j_d_hastings, there are a lot of materials that are safe for laser use, and several that aren’t. @jordanloshinsky put together a great Link Repository that rounds a lot of them up, along with other useful information. (Click on the Materials tab for the safety info.)
But you should be safe if you stick with buying laser-safe materials from a company that sells materials for lasers. (In other words - might want to avoid EBay purchases at first, and stick with Burlane.)