If there's a larger transparent water-tight container on the market, I haven't seen it. Looks like it'd need three ballast pods for a total of 30lbs. This electric heater pad would fit neatly inside on the second floor where air would insulate it from losing heat to the outside water. Should be possible to put together for less than $300. Right now all donations are going to more helium for Skyhab, but if someone wanted to be my secret santa and buy this drybox I'd commit to building a new 2-story Hampture.
