A long time ago, Edward Scientific was the company to go to if you wanted to experiment with science or electronics. You could get just about any kit on the market, as well as lasers and splitter lenses for holographic photography.
America's got nothing on Japan for teaching people science. Want a piece of gear to build your own telescope or whatever? Go to Akihabara. Want a DIY magazine to show you how to build your own class 1 laser or RC space shuttle? Go to any book store - it'll be right there on the shelves. Want to do something a little simpler but still learn a lot? Go to Gakken.
Gakken is a publisher of textbooks and DIY magazine books (AKA: mooks). There are currently 22 "Adult Kit Mooks" on the market, from simple synthesizers and vacuum tube radios, to theremins and a build-it-yourself film projector. Most mooks in this series are in the $15 to $25 range, and new ones come out once every few months. For Christmas, I received two of these mook kits.
First is the "slow clock". This is a simple 1-hand clock that teaches how timepieces work. The pieces are mostly good-quality plastic (meaning that they won't quickly break or deform) and the kit takes about 2 hours to assemble. The drive mechanism is a hanging weight, about 10 ounces (which is a 500 ml bottle filled with water). The clock measures in 1-hour increments, and the string is long enough to let the clock operate 5 hours without winding. There's no housing, so the ticking is a bit loud. It's not the greatest clock you could buy for the money, but that's not the point. You build the clock to learn how clocks work. Afterwards, the mook also shows you how to modify the clock to turn it into a chime.
(DC motor car)
Second is the DC motor car. Here, we have a DC motor that uses a coil to attract one of 6 magnets on the drive wheel. As a different magnet on the wheel approaches a reed switch, the switch opens and the coil turns off. Inertia causes the wheel to keep spinning so that the reed switch closes again and the coil turns on to attract the next magnet. Kind of like how the propulsion on maglev (magnetic levitation) trains work. The motor uses a single AA battery, and it goes through batteries fast, plus the gearing on the drive pulley results in the car moving fairy slowly forward (you can swivel the front axle to make the car go in a circle). But again, the point is to show you how to make such a motor. You even have to hand-wrap the wire on the coil yourself. This also took about 2 hours to build the full kit (not including the time for unwinding and rewinding the coil because I got it wrong the first time).
When you're done, you still have the mooks to read. The first part of the mook talks about the practical applications and long history of the subject (in Japanese of course). Then, the rest of the mook covers other DIY projects (like making a small wind generator, or a really complicated paper airplane).
There's a higher-end series of kits for building your own steam engine or dirigible, but they run well over $500 apiece. The steam engine outputs 3 watts at 12 volts, and costs roughly $1600.
I like this lower-end gakken series of kits, because they're fun, inexpensive and just a little challenging to build. I'm hoping to get my hands on the Edo-era spark generator next.