There's not anything made specifically for Glowforge, and most other lasers cut so much faster and with much stronger air assist that their operators don't need to mask everything like we do. Their cuts come out clean without it.

Several Amazon sellers have added that disclaimer for liability reasons -- because loose masking tape can catch fire in your laser and cause thousands of dollars in damage.

That doesn't mean you can't use it. Any paper masking/transfer tape will work.

I use the Vinyl Ease paper tape which is available on Amazon.