Step 1: Materials
- A Tesla coil - $20 - $50
- An Arduino - $35
- A Maxbotix sonar sensor - $25
- One 12V to 120V relay - Free to $6
- One transistor and a resistor to match the relay - Free from old electronics (See this Instrucable for more info.)
- 12V Sealed lead acid battery - Don't you have one already?
- Various wire