any ideas or links to instructions welcomed. I fancy a new project and mate can do machining for the housing.

search for trout on the forums and hand over the cash. kind of been done before. i admire you if you do it and come up with something original.

Have a read of this bike light forum

led-tech.de is a great source for leds, lenses and (to a lesser extent) drivers. They do some nice modules which make construction easy.

I built my own pepper pot style light 2 years ago and still going strong.
Built nice and simple with just a on/off switch and basic driver without different modes to keep it robust

As mentioned try the CPF forum and also try this one http://forums.mtbr.com/forumdisplay.php?f=124

Chris AKA Troutie is a great guy to deal with and was more than happy to spend a few hours showing me the basics.
My only advice to you is once you start building it is very addictive

It’s hot, it’s bright, it may catch fire… WCA to the thread please – just as an example how not to do it! 😉

Start with a 4000 lumen light and cut it in half with a hacksaw.