For this Instructable you'll need a few things.
- A string of Christmas lights
- A ping pong ball for each light on the string
- Drill and drill bit (or other implement to make a hole in a ping pong ball)
- Hot glue and glue gun
When researching this project I found that you can get a gross(144) of ping pong balls for under $20 including shipping on eBay.
Make sure the string of lights you use is in good condition. Check for any electrical shorts or overheating bulbs before starting.