I'm building a fountain for the garden and need a short length (1m) of 10mm hose / pipe and a male-male connecting thing (apologies for my sophisticated technical jargon ) and a couple of clamps.

Where can I get this in Bangkok?

I don't frequent hardware stores that sell male to male fittings. If you mean male to female I can offer a suggestion... Try global house. They sell irrigation products and carry some small pipe sizes from the super products line.

Just about any place that sells PVC pipe will sell connectors.

Most branches of HomePro have clear pipe of various sizes and hose fittings in a limited range. As DL notes the irrigation section could be a source for those smaller sized bits not available in the plumbing section.

Most of these stores seem to have similar bits scattered around so finding 1/2" pipe connectors next to 3/4" pipe connectors is unlikely.

You may also score at your local mom-and-pop hardware emporium, take pictures of what you need, you may be pleasantly surprised what they have in a cobweb covered box at the back.

The tropical fish section at Chatuchak (Mo-chit) market is also worth a look for that sort of thing as well as pumps and fountain heads. The fish section is open every day not just weekends.

Quick update I couldn't find exactly what I wanted so I devised my own solution.

My cheap 650 Baht solar powered pump with fountain head, has in fact water lift to about about 45 cms, but the pump is very small.

So I inserted an upside down flower pot in the vase, put another one (right side up) on top of that and filled it with enough small pebbles so that the height that allowed a third pot (also right side up) could sit on that and be level with the rim of the vase, into which sat my pump secured in place by a few more nice white pebbles.

I then filled the whole vase full of water and adjusted the depth of the fountain so that the water would fill back within the mouth of the vase.

Its not perfect, we occasionally have to top it up with water but for the most part it works.