Step 1: Get the Materials
2 2-litter pop bottles- You can use any size, just make sure both are the same size, though. I like 2-litters best because they go the highest. Try experimenting with different sizes.
Duct tape- The ultimate tape.
Hot glue gun with glue for it
Cardboard- Find the sturdiest.
After you get the hot glue gun, you should probably plug it in. This way it's hot when you're ready to use it.