In case anyone's interested, I found this online and think it's a really great idea. Instead of the typical sand ceremony that simply involves pouring sand into a vase or bottle, this company sells hourglasses that can be engraved with anything you want and there's an opening in the top where you can pour the sand during your ceremony. It makes for more of a unique keepsake and decorative accent to your home than just a vase filled with sand and I just love the idea of pouring the separate colors into the hourglass and then watching them combing as they filter through the center.
Here's the site in case anyone's interested:
http://www.heirloomhourglass.com/