EDIT: Updated with new price, links, and relinked pictures =)
Here's something I put together earlier this winter. It has worked flawlessly and allows me to use the rain collector year 'round as well as provides me with an approximate liquid equivalent for snowfall.
The items needed to construct this are:
1. A 25W heat cable for use in terrariums:http://www.amazon.com/Zoo-Med-Reptile-Cable-15-Feet/dp/B001OVBEEK/
Note, that while the cable is 15 feet long, only about 6 feet of it is heated. There is a blue line on the cable that indicates the beginning of the heated portion.
2. Foil/adhesive backed foam pipe wrap. 1/8" thick x 2" wide x 15' longhttp://www.hardwareandtools.com/invt/9320524
3. Notebook paper
4. Scotch tape
5. Tin foil
Begin by taping several sheets of notebook paper together in order to make a template for the insulation blanket:
Place the paper in the bucket as shown and trim it to the edge of the bucket. You should wind up with a template that looks like this:
Attach this template to a sheet of aluminum foil using scotch tape:
Trim the foil to match the paper template leaving a slight overlap so that the paper stays attached with the scotch tape:
Completely cover this paper/foil template with the insulation tape:
This is what the backside should look like:
Trim the foil tape to match the paper template:
Gently roll this piece and place it in the bucket. Trim it so that it fits snugly and doesn't interfere with the bucket's latch mechanism.
Once it is trimmed to fit perfectly, remove it and attach the heater cable to it using scotch tape. Remember that only the last 5'-6' of the cable is heated, the rest is just a lead. There is a small blue line that indicates the beginning of the heated portion:
Place the entire assembly back into the bucket. In order to prevent the lead from interfering with the latch, you need to make a small slot in the bottom of the bucket for the cable. No more than 1/8" wide by 1/4" tall really. I used my Dremel, but a red hot paring knife would do the trick as well.
So there you have it. Like I said, it's worked great. I have a switched exterior outlet that I plug an extension cord into and run over to the station. When there is snow in the forecast, I switch it on. I tested it inside and measured a 20 degree rise in temperature inside the bucket. (65F to about 85F). Outside it doesn't even feel warm to the touch really, but it does melt any and all snowfall.
It is nice, because I will be able to easily remove it and store it come summer time so there won't be a cord hanging out of it all year long.
I looked into some thermostatic control options, but was unable to find anything that was small, inexpensive, and that would stand up to the wet environment in the bucket. That's about the only improvement I think I could make. But... this is version 1.0 and I welcome all of your feedback!
Hopefully others of you are able to make use of this =)