Probably because it's best suited for changa/enhanced leaf. Most changa users seem to have an abundance of commercial implements or at least one highly effective device. Though your device can apparently be outfitted for use of freebase, in SWIM's case, he has a less bulky homemade device that works perfectly for him; however, he's still interested in the prospect of making a similar device to "the key" using porous ceramic to diffuse the heat, rather than a screen. The use of ceramic would make it a true DIY version of the VG and would also help prevent the device from getting hot (ceramic is an excellent heat-sink). You may be able to find porous ceramic at an aquarium supplier's.
The engravings are very cool, by the way.
The engravings are very cool, by the way.
