Using a small, cheap space heater from amazon ($17 or so) we created the design that can be substituted for an $800+ device. Link to heater: https://www.amazon.com/Honeywell-HCE100R-Heat-Ceramic-Heater/dp/B00I4UVGHO/ref=lp_510182_1_3/159-0320742-4984928?s=home-garden&ie=UTF8&qid=1481207899&sr=1-3&th=1