Hi. I've searched through the forum and other internet resources and found several threads and sites, but haven't yet found any really detailed technical info. I'd like to build a series of cloud chambers. I'm an designer/researcher, with an interest in history and philosophy of science. Does anyone know of some good resources that describe ideal temperature gradients (I've seen -40 C toss around), alcohol types (some recipes call for pure isopropyl, others for ethyl or methyl), discussion of chamber size (several recipes give very specific chamber sizes with no discussion of these were arrived at), etc. Ideally, I'd like to be able to run a chamber continuously. I've seen at least one model that used a (custom?) refrigeration unit. I've just begun to do some research into refrigeration plates, but still haven't managed to find a straight-forward resource on these. I've no budget for this. Obviously, I'd like to get away from dry ice. Do affordable cooling plates of a reasonable size (a square foot or larger) exist, that can achieve the needed temperature gradient exist?