Has anyone got experience of 3D printing?

Just looking into what it can do.

Not really...

http://www.livescience.com/34551-3d-printing.html

I wanted to make something and was quoted prohibitive prices to have it made because I needed a different machine to be made to make each piece but maybe I can do it with a 3D printer instead.

3D printing has the potential to be brilliant, you can make almost anything from any material which can be a liquid that can set solid and strong, so that's most polymers, some alloys and apparently even carbon fibre.

I've not used one myself, but I have used a CNC milling machine and I would guess it would be similarly complex.  It's not like normal printing, more like CAD with physical results, so you need to be able to think in three dimensions, something which is surprisingly tricky to do.

I think the hardest part would be thinking of something useful to make with it.

Here's what I want to do:

I want to make a leakproof moat 30m in circumference a few inches wide and a few inches deep. I want to be able to dismantle it so I can transport it easily. One company said they could only make each piece 60cm and I'd need 50 separate pieces and a machine to make each piece. I figured maybe 12 or 13 as each piece would have an exact match on the other side of the circle. I figure with a 3D printer I can make the whole lot fir the price I was quoted for one piece!

Don't ask what it's for!

Your French châteaux?

Keep the riff raff away....