I'm building a simple illusion and I'm looking for a way to connect two rubber bulbs by a rubber tube, so that one of the bulbs will be deflated most of the time, until I squeeze the other bulb, and then the first bulb inflates. (Useful for causing 'remote movement' without having to buy any electronic remote controls.) What's the simplest way to go about this -- are there pre-existing products that do exactly this? (I can't imagine what they'd be used for, but just checking.) If not, what's probably the simplest way to make something like this?

What I'm doing is taking a magnetic levitation product like this:
http://www.fascinations.com/unique-toys-......tage.htm
and putting the levitation platform inside a wooden nightstand so it's hidden. Then the magnetic disc which floats above the platform, gets hidden inside an object that's resting on top of the nightstand. The levitation platform inside the nightstand is resting on a flat piece of wood, and under the flat piece of wood is one of the rubber bulbs. Then when I squeeze the other bulb from some discrete position outside the nightstand, the first bulb inflates, the wooden platform moves up, the levitation platform moves up, and the object on top of the nightstand appears to lift itself up and levitate (!).

(Open to other suggestions on how to make the effect work -- I don't know if anyone has ever built something like this that relies on commercially available magnetic levitation toys.)

Yeah...they do exist.Can you imagine the kind of bulb the Doctor squeezes when taking your blood pressure.They usually have a one-way valve at one end and an air intake at the other.
Now the other way I have got around this is by using the kind of flat rubber bottle you fill with hot water for having near your body for warming you up - in Britain we just call them a 'hot water bottle' well they have the advantage of being very robust and will withstand a great deal of rough handling so you can have one hidden somewhere and just stand on it to apply pressure.They seem to have a very strong plastic stopper which can be drilled through for fixing tubes....of course using one of these is only any good if it can be kept out of sight.

Hope this helps in some way

The original name for this was as a "plate palpitator," or "plate lifter." It was first used by mediums in seances to make things mysteriously move around the seance table, but today it is mostly found in joke shops for the prank of making someone's dinner plate jump up and down on a dinner table.

Here's one source for the joke version: http://www.mooncostumes.com/item/8224

How stable is the Levitron? Any experience I've had with these is that they take a lot of trials to get it floating properly, and only when you had the base perfectly level. Mine came with adjustments for each foot. Is your toy of this type or does it have some sort of electronics to keep it steady. I ask this because any movement from underneath, especially using an inflated bulb would cause the thing to become unstable and you'll lose the levitation. You'd end up completely frustrated and deflated (Pun intended).

However, for more stability you could try a mini scissor lift
http://www.google.com/products?q=mini+sc......0QzAMwAA

I built one of these with my son recently - very easy. It uses to syringes of water connected through a tube.

How about using a cable to actuate this, like the kind model airplane folks use? Small diameter cables inside of plastic tubing can push and pull, and you don't have to worry about leaks.

Ross

Yeah, leaking could be a problem with my suggestion if you are carting it around.
You'd still want to be very careful how you moved it because these things are not inherently stable.

Ear syringe, or "booger ball" as some call them, assuming that size is not an issue.

MagicMatthews --

Yeah the original Levitron, the spinning top above a magnetic base, was very unstable and could not be moved side to side or up and down without toppling the spinning top, unless you were very careful.

I have their new products, the Levitron World Stage and the Levitron Revolution, and those you can move around without destabilizing them. And they come with a globe that floats above the platform, but you can pop the globe open and taken out the floating disc inside them, and then mount other objects on top of the disc. (The new products require a power source though where the old Levitron did not.) So I'll try to figure out how to hide the disc inside an ordinary-looking object like a cookie that can be levitated off the table top.

The scissor lift sounds like a great idea! So does the plate lifter. They're cheap so I'll probably get one of each and experiment.

The cable inside plastic tubing sounds like a good idea, but I'm not skilled enough to take a tube with a cable and make it into something that works; that's why I was looking mainly for pre-built products. (I didn't even trust myself to build my own plate lifter out of two plastic bulbs and a tube, after all )

When I hear "cable inside tubing", I think "bicycle brakes." Perhaps that would be easy to modify. Just a thought!

:)