how have you identified a demand for 3d printed products ?
Just curious as I don't see any real demand in the uk.

Most people simply do not know that 3d printing is an option, or what it can do.

A service is a good idea. Gives a lot more scope and greater opportunity to find a niche product that actualy might make a profit.

3d printed toys probably not such a good idea. The plastics and printing are generally not certified for public retail. Though I suppose that depends on which country you are in. If you are not subject to EU laws - then it's probably okay :-)

As for printers, you need as many as you can get.
Bear in mind that a printer can take a few hours to make even a relatively small item, on up to 10-12 hours for something medium sized, the more printers you have the better.

What you need is a specialist Geek/Nerd/enthusiast who already knows about 3d printers.
Reason being the best way to get a lot of good printers fairly cheaply is to buy kits and build them. For which I would recommend someone who had already built a printer from scratch.

So what sort of toys were you thinking of ?