Anything that is based on controlled heating by convection instead of conduction. In other words, a method based on hot air passing through the container as opposed to a hot surface that directly touches the material being vaporized.
You can use a classic vaporgenie that is made of wood if the problem is simply the glass.. Its not as good as the GVG but its still better imo than most of the other common methods like a bong, the machine, lightbulb vape, etc...
You could in theory just fit the top ceramic filter of the vaporgenie/gvg in another pipe or bong of matching dimensions and that'd make it vaporizing pipe instead of combusting pipe...
Also you could check out the
green buddha which seems to be as good as the gvg, but you 'assemble' it yourself. Or you can just get the top part, again, and put that in any other kind of pipe or bong.