How To Make an Udderbot for Under $10

1. Get a glass bottle. The better, the bigger, although the lip shouldn't be too wide.

2. Remove the bottom from the bottle. The best method I have is to boil the bottle in water on a stove for at least 10 minutes. It might help to pour boiling water into the bottle during this time. If the glass is weakened enough, the bottom circle should pop off cleanly with the aid of a skewer poked from above.

(The process can be managed with just the skewering if you are impatient and willing to have a less perfect crack. The process can be managed without a skewer also: prepare a bowl of ice water, and touch just the very bottom of the bottle to the water surface. Many other configurations of heat and cold do the some thing, including this $40 kit which I haven't gotten to work nicely yet.)

3. After cooling, tape up the sharp glass edge with thick, waterproof tape. Duct tape works o.k. Waterproof rubber sealant is more a more thorough alternative.

4. Slide a rubber glove onto the bottom. Size of glove should be matched as closely as possible to the volume and diameter of the bottle. Tape or glue the outside of the glove to the outside of the bottle. Leave no gaps! Make as watertight as possible!

5. When tape or glue is dry, fill with water up to the bottom of the glass.