The multi-color pathway lights we used have a small PCB that controls the battery charging function as well as the "random" color changing function of the LED. You can use clear pathway lights as well - whether to use color or clear is a personal preference. All the "tech" is provided by the pathway light. What we are going to do is to disassemble the light, relocate the LED to an ornamental glass ball and attach a wire hanger to the solar module so that the solar light can be hung from tree.
Step 1: Bits and Pieces
All told, cost for a single light will be roughly $5 each which the major cost from the pathway light. The balls work out to about $0.80 each.
Tools you will need are drill with 1/16" and 1/4" drill bits, pliers, side cutters, hot glue gun, sharp knife, Phillips screwdriver and a soldering iron.