2-Bottle Coke "Hourglass" Ecocolumns

Step 1: Measure one bottle 24 cm from the bottom and the other bottle 10 cm from the bottom.

Step 2: Cut one bottle at the 24 cm mark and the other bottle at the 10 cm mark. Keep these three pieces to make your ecocolumn.

Step 3: Assemble the three pieces into an ecocolumn.