All you need for this is:
- White LEDs
- Sand paper (fine, between 200 and 400)
- Color markers
Once you've got these things you're ready to start!
I bought 100x 5mm LED white on eBay for only $7 (including shipping).
So that's only $0,07 for each LED. You won't get colored LEDs this bright for that price!
You can use any size of LED you'd like. In this instructable I used 5mm LEDs. But you can do it with a 3mm or 10mm LED as well.
The LEDs I had are 'water clear'.
To make the effect of the color work good we need to make the LEDs 'diffused'.
1. We need fine sandpaper to get the diffused effect we want. The best sandpaper to use is some between 200 and 400. The one I used was 240.
Sand the whole LED till you get the diffused LED effect. You can see the difference of a 'water clear' and 'diffused' LED on the photos below.
2. Clean the LED so all the LED 'dust' is removed from it.
I've also attached a battery and made a photo so you can clearly see what the difference is and what cool effect we'll get.