It's essentially just the threaded part of a plastic bottle sized to fit by heating it up attached with a tie-wrap.
The tools I used:
a pipe wrench
a utility knife
and a iron saw
The materials used:
a plastic bottle
optionally some kind of rubber
Step 1: Cut the Top Part of the Bottle
Being careful to only cut into the bottle and not into yourself, cut of the top of the bottle. Aim for the place just below the rim where the plastic gets thinner. If you have too much excess plastic hanging on you can trim that off too.
Step 2: Saw Out a Section
Using a fine saw like a iron saw or a figure saw, saw out a section of the bottle neck. Use a file or your hobby knife to even out any rough edges.
Step 3: Slightly Melt the Plastic
Using a lighter or a lit candle heat up the bottle neck while squeezing it tight, do this in small increments, keep turning the bottle neck and don't keep the flame on the plastic for longer then half a second at a time, you only want to slightly melt the plastic, not burn it.
Watch out for the fumes, they are not healthy.
Step 4: Fit and Attach
When you are done tightening your new mount be sure to see if it actually fits your flashlight. I only did this at the last moment and thus have a very tight (and secure) grip which makes it a little tough to actually get the flashlight in.
You can then attach the mount to your steering wheel using a zip-tie, this also makes the fit tighter so keep this in mind when tightening.
I put a rubber band between my steering wheel and the zip-tie to keep it from twisting around but I would recommend using a piece of bicycle innertube for this it looks a little sloppy like this.
Your done! You can now go and buy a cheap but bright flashlight (like the one I have: http://www.dealextreme.com/p/torch-light-c78-flood-to-throw-zooming-cree-q3-wc-130-lumen-led-flashlight-1-aa-29095?r=29307820) and light up the roads on your daily (nightly?) bike trips!