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What kind of maniacs use neodynium magnets in toys?? I am working up a prototype product using 1/4 diameter ND magnets, and I am amazed at how dangerous they are. They have roughly 35 times the attractive power of an equivalent-sized traditional magnet. With proper support, an ND magnet the size of a dime can suspend a 3 1/2 pound drilling hammer firmly from the ceiling with no risk of falling. At the least, ND magnets can pinch the heck out of your fingers. I have old tough hands, but a small child could be seriously injured just by handling them, let alone eating them.

They really are amazing little things.

If they ever do manage to build a Heinlein-style "rail-gun" launch system (see "The Moon is a Harsh Mistress", in which it was used to launch ore from the Moon to Earth), I suspect it'll be based on these type magnets.

A linear motor based on a series of "supermagnets" would be a very impressive thing to behold. Instead of using massive amounts of electricity (in short supply in places like "space"), rare-earth magnets could supply the raw force, and a relatively small power supply could neutralize each one, in series (as the "car" passed by), via precisely timed capacitive discharge.

You can "blip" a rare earth magnet for a fraction of a second using a fairly trivial amount of power. It was either Olympus or Canon who used this as the basis for their electronic shutter (I forget which, it's been ~20 years since I've worked on anything like that).

Prior to that development, the standard for electronic shutters was a solenoid that held a pawl/sprag/etc., which, while actuated, held the shutter open.

The longer the exposure, the more current that would be drained out of the battery.

The new design used a combination piece -- a small solenoid combined with a tiny sliver of rare-earth magnet. When the shutter was wound, the solenoid would be closed, and the magnet would hold it closed.

When it was time to open the solenoid (i.e., to release the second curtain), the electronics would send a very short "blip" to the solenoid, with a polarity opposite that of the magnet's polarity. Net result was the magnet being negated, and the solenoid opening as the magnet's power disappeared. It only disappeared for a fraction of a second, but that was all it needed, in order to release the shutter.

So, batteries lasted much longer, and the length of exposure was no longer a major determining factor regarding battery life, because the battery wasn't required to supply a large amount of current to brute-force hold the shutter open.

Now, take that concept, and translate it to a linear motor. Powerful permanent magnets, lined up in sequence, with a coil mated to each one, and a computer timed to turn each one off, in sequence, right when it was time to release it to the next magnet.

These are amazing little things, but they are NOT the stuff of kids toys. Not unless someone doesn't give a damn about killing "other people's kids", and money means more than having even the rudiments of a conscience, and "ethics" means "whatever you can get away with."

Boy, I'd go far in China, wouldn't I. :) (all the way to the organ donor pile, LOL!)