How to Build It
1. Attach a small piece of tubing to the outlet on a 12-volt output pump [A].
2. Add an elbow fitting to the tubing, and connect a length of hose [B]. Run the hose to another elbow fitting, and screw that to a piece of plastic pipe [C].
3. Attach an elbow fitting to the other end of the pipe, and screw a showerhead [D] to it.
4. Wire the pump to a 12-volt car lighter plug [E], and drop the pump in a bucket of water.
5. For a freestanding shower that can be attached to a cooler, add two extra solid pipes with couplers in line with the other solid pipe.