Hydrodynamic Set
ThinkGeek has a 300 piece Hydrodynamic building set ($89). It includes: girders, tank parts, tubing, valves, tube connectors, meters, etc and an electric pump with AC adapter –

Water is everywhere. It covers 71% of the Earth’s surface and composes about 112% of the human body. Gaining control over water would be an awesome super power, but for now we are stuck with using science to master water. Good thing someone invented this Hydrodynamic Building Set. It makes science fun again. But this kit isn’t a simple connect the dots – you have to do some thinking!

The instruction manual shows you how the girders connect, how to build the various tanks, and some rendered images of completed projects – but not step-by-step. Your entire model gets built up from the bottom of the carrying case, which acts as the water reservoir and also has a special footing to be the structure’s foundation. Level by level, you build your support frame and add your tanks. Then connect all the tubes, add in the valves, and turn on the electric pump. If you’ve done it right, you’ll have an awesome construction everyone will marvel at (a little food coloring helps). Fail and you’re all wet – quite probably literally.

ThinkGeek :: Hydrodynamic Building Set – [via] Link.