I haven’t seen this mentioned, so thought I would share. One source I’ve used for materials and ideas in the rotary engraving world is “The Engravers Journal”. There is as much, probably more, about laser engraving also. This is a monthly trade magazine for the engraving industry, pretty heavy in ads and in stories about how to increase sales, but there is a lot of useful information for the hobbyist also.
Website is: http://www.engraversjournal.com
Subscription price is high, but I think they give complimentary subscriptions pretty freely. (that’s what I get) One free source on their site is the “R&P Directory” , which is the digital December 2016 issue listing all the vendors. Much advertising of laser-compatible products. Also have some digital sample issues on the site.