i have decided that i am going to build one out of wood, there are commercial wood smokehouse's and as far as i can tell wood will spontaneously combust at or around 380f and as i will never have it above 225f i do not see any harmful effects from that, the wood will need to be cured first (smoke the hell out of it) before i put any food in there, but also after i smoke the first food product i will have it tested to see if there is anything wrong with it. i cant see any issues with it as we use wood chips to smoke food in the first place, the wood enclosure should not do any harm, i have seen and been told to use a hot plate in a cardboard box, that has glue and garbage in it and on it, i will put this wood smokehouse together with out the use of wood glue or any other chemical they may effect the quality of the food i put into it. i will use stainless steal screws, only on the outside and make sure absolutely nothing goes through to the inside, i do not wish to poison my self or any one else that may eat anything i smoke in that wood smokehouse. like i said i am going to make sure it is 100% safe before i start smoking eatable food in it