To make these fancy ice lanterns you need:
1. below freezing temperatures (or a really big freezer)
3. a bucket
Step 1: Fill your bucket(s) with water
Step 2: Put the bucket(s) in a cold place
Step 3: Let the water freeze - but not completely!
You want the water to freeze to about a 6cm (2 inches) thickness on the top and the sides while the center of the bucket remains liquid. This happens because the water freezes from the outside in. To find out if the lantern is complete look down into the bucket through the ice to gauge how thick the walls. It's a bit of a guessing game but it usually works.
The most important thing is to not let the water freeze solid. If that happens you end up with a big lump of ice and the bucket will more than likely crack.