For our thermos we managed the least amount of heat in 45 min, Our price range had to fall under 3$. We created 3 prototypes to experiment on. We agreed that prototype number 3 was the best prototype Although it came to 3.68$. We used 10 inches of tin foil, 2.5 styrofoam cups, 2.5 inches of foam underlay, and 5 inches of tape. Prototype 3 was successful we lost 26 degrees celsius in 45 minutes. The first 2 prototypes that we created lost a substantial amount of heat in only 20 min so those were busts. There were 3 designs we had planned out the first two prototypes were created without lids that why they lost the heat because there was no lid to trap the steam and the excess thermal energy inside the cup.