An entire website is devoted to one unique DIY holiday ornament: The Sparkleball at sparkleball.com.
The sparkleball is made with 50 clear drink cups stapled together to form a ball. Inside your ball go some of your stash of mini lights.
The result is exceptionally sparkly and has the advantage of using all those lights in storage.
Plus, the sparkleball can be useful during a summer pool or patio party, not just Christmas.