This project was made at TechShop - Detroit for a school play. They needed the Wicked Witch's hourglass. After designing the top and bottom pieces (same piece used twice) in CAD (Autodesk Inventor is available to all TechShop members for free), it was easy to fabricate using the ShopBot CNC Router at TechShop.
Our version is not as ornate as the original movie version, but it actually works, and was very inexpensive.
3/4" particle board
(2) 2-liter soda bottles with caps
(1) 1" PVC coupling
(6) 1" Drywall screws
ShopBot CNC Router
Drill with various bits
Hot glue gun
Step 1: Cutting top and bottom pieces
Cut the bottle profile 1/4" deep with a 1/8" end mill or Rotozip bit. The pockets for the ballisters can also be cut 1/4" deep.
For the edge detail we used an Ogee router bit. Because it was the type that has the bearing on the bottom (which we removed), it doesn't cut the bottom of the shape, so we programmed the ShopBot to cut the outer profile the full depth of the workpiece (3/4") first, then followed up with the ogee.
Pay no attention to the other shapes in the photos, as we were cutting three different projects simultaneously.
Step 2: Secondary operations on top and bottom pieces
The side that the ShopBot cut is the side that faces inward towards the glass (both top and bottom), so on the back side, use a countersink bit for the drywall screws.