This simple little floating boat bounces off walls, can be steered with a flashlight, and won't hit something head-on.
Step 1: MATERIALS
hot glue + glue gun (silicon optional)
two small DC motors
two water bottles
two small propellors
arduino + USB cable + computer
a plastic box
a 9V battery + a connector
a power diode (like 1n4004)
a soldering iron + solder
a MOSFET transistor or TIP 120
2 few switches + 2 photocells
Step 2: Put the motor in the cap
2. Poke a hole in each cap
3. Apply hot glue to the inside of the cap, but not on the hole. Slip the motor shaft through the hole. When dry, the shaft should spin freely.
Do this with both bottle caps and motors.
Step 3: Tape the water bottles together
Step 4: Solder leads to the dc motors if there are none
Solder on long (about 10") leads to the motors, if there aren't any.
Step 5: Cut a slit in the water bottle
This is the hole through which the wires from the motors will poke through.