In this Instructable, I'll to show you how to build many projects that use a simple hydraulic system that kids in elementary school can build. Each step will show you one of four machines that use the same basic mechanism.
These are the essential materials, but you could of course add to this list.
Craft sticks, craft cubes, cubes with holes, skewers (less than 1/8" diameter), 10ml luer slip plastic syringes, 1/8" vinyl tubing, cable ties, tape, and hot glue.
First thing's first: How to make a hydraulic system
Step 1: Simplest machine
The video gives you an overview of the simplest hydraulic machine - the photos tell you how to build it! I've had kids as young as 1st grade build this project.