Sintra is a very dense vinyl foam that comes in a variety of colors and thicknesses and is easily glued and milled. I was hoping it could be a potential Glowforge material. So I ran a quickie test this morning.
In a word, nope.
It can be cut and engraved at reduced settings, but it changes color, heat-curls the cut edges, produces lots of soot and Gawd-knows what kind of poison gasses from the cutting. At full power cutting, the residual heat from the laser striking the steel crumb tray matrix actually traveled into the piece, making a burned grid around the edges.