very very simple solar cell pendant.
Step 1: Ingredients
1. Monocrystalline Silicon solar cell 5.5V 80 mA
performance parameters: Operating voltage: 5.5V Working Current: 80MA Power : 0.44W Dimensions: 77.5 * 40 * 3mm
2. High-Brightness 7-Color 5mm Blinking LED
4. get 3D Files from http://www.thingiverse.com/thing:714143
Step 2: 3D Print of Pendant Heart
get 3d files from http://www.thingiverse.com/thing:714143
Step 3: Soldering & Assembly
you may need to add resistor and 3v zener diode for led protection, but i didn't use it because i think the solar cell has low efficiency.
Step 4: Pendant Assemblies to a Necklace.
and then attach pendant to a necklace.