All you need is a large number of dead CDs and a supply of 8" cable ties. DVDs are pretty, too. Put two CDs together shiny side out, loop a large cable tie through the hole, and then through the cable tie that runs through another pair of CDs (make one pair stand-alone first). "White" cable ties will eventually disintegrate in the sun, but so will CDs at some point. Black cable ties (UV-resistant) will last longer than the CDs, for sure.
You can also connect two pairs together with a longer cable tie--perhaps 11", but maybe 15". Test. These cable ties are more expensive and a bit harder to find. The 8" cable ties are sold everywhere, in bulk packs.
Christmas lights in the trees make them sparkle even more at night. The chains will set off the motion detector. Birds are not deterred in the least.People ask about the CD chains that decorate my yard from the Sunday after Thanksgiving to just before the daffodils bloom in March.