sorry for writing urgent. i live near walmart and i've seen some big rubber maids there. is there a sertant model or not i know it's got to be 3 feet by 18'' wide but how high. glass is really exspensive and real heavy i heard rubber maids are good for humidity. can i use a heat pad or will it melt the plastic thank you for all your help i hope you will help me in the future thank you so much