The majority of my inspiration for this fountain is from Arthur Ganson's "Machine with Grease", which unfortunately doesn't have any video online of it working (Jesse showed it to me on the DVD). It's basically a machine with a moving pump that cascades thick grease over its own workings. I can only imagine what it smells like, though!
I had learned about sodium polyacrylamide crystals from a 9th grade science teacher (thanks Mr Ricks!) - they're these crystals that can absorb something like 400 times their own weight in water, forming clumps of gel crystals that are very soft and gooey-feeling.
These are the crystals in their unwatered form. You can find them at home and garden stores as an additive to soil that makes it hold water better. I've also been able to find them on eBay as "soil crystals".
Just dump them in warm or hot water and over several hours they will absorb all the water and become clumpy gel. What we want is goo, so have at them with a hand blender (I love hand blenders) or a normal blender.
I decided to motorize a pump modeled after a basic bicycle air pump - the center "shuttle" moves up and down, with a valve in it to make sure fluid only goes up. There's another valve at the bottom with the same orientation so that the pump both expels goo at the top and draws in goo at the bottom when the shuttle is moving up - the shuttle moving down is just a 'reset' cycle where the shuttle moves below the goo that's already in the tube.
The design of the valves is fairly basic - two brass flaps in the tube flip up when there's pressure below them and flip down against an O-ring when the pressure's above them.
Then wind the fishing line around some spools and connect them to a motor. I use a 30 RPM AC timing motor from All Electronics to turn the spools. This motor has a great feature (for this at least) where when it encounters resistance (for example when the shuttle hits the top or bottom of the shaft) it will reverse direction. That's perfect for my goo fountain!
(You may also remember this motor from my creation The Balltrack.)
That's all for the goo fountain! If you like my stuff be sure to check out my other creations, as well as the other beautiful creations by other members of the site. Check out the random creation bar to the right, I'm sure you'll find something that interests you!