Dude, be more specific, dx has tons of different flashlights, post a link for the flashlight you want.
As for the size, it's written right there in the first post, but here's a pic of a drawing the size of the driver compared to a quarter.
Mine are 0.8125" x 0.625" x 0.5625" & capable of 6-320mA. Should use a heatsink for anything over 100. I just need some more parts and I can make ya some.
So they're not 6", they're 0.6", or rather 1.76 centimeters. i.e. Very small.
If you wish to make your own device then my advice to you would be to pay for a couple of his drivers. Wait the requisit amount of time for them to be manufactured and distributed, which could, appreciably be a little while off yet and sit tight.
Alternatively, if you hang in there you'll see lots of people selling BR flashlight-based lasers once these small drivers come into circulation. (Kenom etc have bought into ~100 of the drivers).
Do you have a BR diode yet? As the harvesting and mounting process of these is probably not something that can be tackled with the greatest of ease either.