While cutting up 2L bottles for hydroponics planters, I found that they are of slightly different diameters and Pepsi bottles slide inside Coke bottles, when the ends are cut off. The flares at each end of the Pepsi bottle act as a slide "limit", but also give strength to the "structure".

The uses are many and the resulting containers are both reusable and disposable.

Step 1: What You Need

1 ea 2L Pepsi bottle
1 ea 2L Coke bottle or similar.
1 ea Utility Knife

Step 2: What You Do

1. Cut Pepsi and Coke bottles in half as shown.
2. Fit halves together as desired, depending on end function, as shown.

Uses - Terrarium, food storage/protection, yarn holder, hamster wheel (drill air holes), picnic/camping storage, bread box, bug cage, lunch box, etc .....