By the way, this is my first instructable so be nice! ;-D
Step 1: Getting started!
So... what to do? Just build one! It's really easy and effective plus you a reusing things you would probably throw away!
What do we need:
1.)_An empty bottle_; One small soft drink, water or whatever bottle with an screwable cap will do!
2.)_A clean plastic bag_; A normal grocery bag will do, just don't use a really thick plastic bag, it's worse for squeezing!
3.) A knife, cutter, scissors, anything like that.