I'm making an Ice Age cake and I want to decorate the borders of the cake w/ some edible glass tinted blue to look like ice. Does anyone have a recipe for edible glass or sugar glass that can be left out at room temperature for longer than 15 minutes without becoming soft???

Isomalt colored will work, but it will set hard like hard candy, as will melted sugar, both can be used to make edible ice/glass.

Ditto on the isomalt. I did cast sugar on the snow queens palace cake in my pics for ice--worked great, but the "ice" had a slightly yellow cast. If you use isomalt, it should have less color (also Isomalt will hold up better to humidity and will be less likely to get sticky.)