This was an inter­est­ing find yes­ter­day.  It is a Ceram­ic Planter Heater that uses a can­dle to heat the core which is a steel bolt, wash­ers, and nuts, which heats three lay­ers of ceram­ic planter.  The ceram­ic is dense and hard, holds, and dis­trib­utes the heat even­ly.  Check it out.  While there are no instruc­tions on how to build it, the illus­tra­tions show it is not brain surgery.  I may make one and try it out.  In fact I may make one large enough to han­dle a ster­no heater and see how warm it gets.  If it works, maybe I’ll make a few to keep in the clos­et or to take one camp­ing with me for those cold nights.

http://heatstick.com/_KanHeet01.htm