My mom's coop is off the grid, so a DIY 12VDC water warmer is needed for the winter here in Nashville, TN. OK, it took some doing with input from a few others here to successfully put the plan together. Parts List: - Automotive 1157 dual lamp & brake light bulb 27W. RockAuto.com $1.60+s/h for 10. - 6-inch diameter X 3-inch deep round cookie tin. 0.36 cents holiday clearance from walmart. - 50ft speaker wire. Big Lots for $3. - Automotive 1157 socket with foam seal. Advanced Auto/Auto Zone/Napa ~$5. Doorman p/n 8520 - Scrap wood from projects or 2X4 to frame the cookie tin. Lowes one 2X4 ~$2.79. one picket fence rung ~$1.29. one 1/4-inch thick piece of wood to adjust the cookie tin height. - Finish nails & screws. 6-finish nails for the 1/4-inch wood to tack down. 10 2-inch deck screws (nails will work as well). If you are like me, there are always spare screws/nails from other projects. Under $20 basically. Making the frame to support 3 to 5 gallon water feeder: Cut the picket fence single rung board to make two 15-inch pieces. This is the base. Cut the 2X4 for the 2 left side pieces 6-1/4-inches Cut the 2X4 for the 2 right side pieces 9-1/2 inches Cut the 2X4 for the top and bottom pieces 11-1/2-inches Depending on your acquired cookie tin, the rectangle section will need some wood plank to raise the tin so as to allow the tin top to be flush to 1/8-inch higher than the frame. The inside area to house the 6-inch diameter tin with protruding 1157 socket is: 6-1/4X8-1/2 inches. Note, if you have a larger tin, make the adjustments to sizes. However, the 6-inch tin is IDEAL for the 12VDC power and heat generated in a concentrated area. Using the screws and nails, frame everything together. For the cookie tin, use a 1-inch spade drill bit to make the hole. Ideally, a corded high speed drill works the best. A cordless drill may give so-so results. Also, make sure the point on the spaded drill is very sharp. A dull tip will skip and slip really bad on the circular tin surface and make you very fustrated. Once the hole is in, use a round drill grinder bit to smooth down the sharp edge if any. Lastly, these 1157 socket are 3-pronged locking to a rear tail light assembly. So, using a 1/4-inch width drill bit create a knotch at the 12 noon position of the hole . No need to make 3 knotchs since a little wiggling of the two slips in and the top third one falls into the cut area. Then make a twist with the socket. One the frame, drill a 3/8-inch hole on the side the socket wires protrude (right or left, your choice). This will allow the wires to sneak out of the enclosure. The 1157 bulb wires are black = ground and yellow = positive full brake 27W. The brown = positive lite at 11W. FYI --- if your climate area is colder, you can wire both the yellow and brown together for 38W for a warmer. This will take more battery juice to run. Talking about the juice to power the device ... Now, there are several options to power this water feeder warmer. Battery, wallwart plug to house outlet, generator, etc. Another item to know about, keep the 12VDC battery close to the warmer since power loses can happen over the power wire. About 25 feet of speaker wire would be about the maximum from a battery to have several days of run time before charging. As for my charging needs, a 20W solar panel works best with the thermo-cube. Typically, the automotive solar trickle chargers come with a PIV diode (peak inverse voltage diode or known as a Bypass Schottky Barrier Diode). If you go solar with a bigger panel make sure the PIV charging diode comes included with your panel. This way, you will not need to do the scientific math formula to have the power only go one-way in the circuit. Also, the trickle chargers have a mini-circuit that works as a charge controller too. Check out Harbor Freight or other online sources for solar solar panels (http://www.unisolar.com.au/Catalogue.html US-21 is mine). If you live up north with less sunlight, wind power works the same. Get ideas from Gotwind.org The For Sale / Election signs work great as the rotation blades to a 12VDC motor that can work as a generator. (Rotary Sign generator, scroll down to the AVI file on the page http://gotwind.org/diy/latest_experiments.htm ) Hope this gets some ideas in your head. The project is very cost effective. The power source may not be. However, the option to be off grid with a battery source is attractive. A deep cycle trolling marine battery runs about $89 at Advanced Auto. Their AutoCraft is rated very high for reliability and longer life. This baby can power many 12VDC products since it's 160Amp/hours and has around 800CCA. For marine or RV boondocking, this is the battery of choice.