Things You'll Need
Instructions
Remove the lid and retain. Do this with one bottle at a time rather than removing the lids of all the bottles in one go. This will avoid mixing up lids and losing track of which goes with which bottle.
Place the bottle upright on a bench or table if the bottle has ridges. Grip the bottle firmly around the neck with one hand and the base with the other. Use your weight to collapse the bottle. It will crush along the ridge lines. Replace the lid.
Lay the bottle on its side if it is smooth-sided. Place the flat of your hand down onto the bottle two inches from the base and squeeze the bottle flat. Fold the base of the bottle down flat on top of your hand.
Turn the bottle over while keeping the base squashed flat against the body of the bottle with one hand. Continue crushing the bottle by folding the base over and over, squashing and bending the body of the bottle as you go. You are aiming to make more of a zigzag shape than a concertina. Once the bottle is flattened, screw the lid back on.
Use air pressure to compress the bottles in a more exciting way. Fill them a quarter full with boiling water and swill the water around while being careful not to burn your hands. Pour out the water and immediately replace the lid. Toss the bottle into a sink full of very cold water.