Everything is about experimenting so this is just a guideline on an idea and can be modified to fit your needs.
Silver bowl, depth is dependent on you
4 brass light fittings (works better than ceramic or plastic, will also depend on the amount of space in the bowl)
Plug and switch
Nut and bolt (bolt must be able to fit into a female to female spigot)
Female to female spigot (I use this one http://www.camerastuff.co.za/shop/light-stand-spigot-female-to-female.html)
Remove fittings and in the middle of each pair of markings make another marking. This will be for the wire to go through.
You will now be working from the inside of the bowl as you attach the fittings. Attach the wire to the first brass fitting and place through the middle hole in the bowl and line up the brass fitting holes with the holes on the bowl. Now pop rivet both side of the brass fitting to the bowl.
Repeat this for the other fittings.
I used the glue gun to glue the middle openings where the wires go through to prevent the wire moving or being damaged.
Drill a hole on the side of the dish, this for the bolt and nut in order to mount the light on a stand. A washer is used to stabilize the light and add strength.
Attach the female spigot to the bolt on the underside. I use the female spigot for attaching to my Phottix Varos Hot Show Mount Clamp with Umbrella Holder http://www.camerastuff.co.za/shop/camera-stuff/flash-stuff/hotshoe-flash-brackets/varos-hot-shoe-mount-clamp-with-umbrella-holder.html. I had to reverse the holder to get more flexibility for the light. The female spigot fits neatly into the holder, which is why I chose to use it. Attach plug and switch to wire.
As said, it's a basic light. The one thing you might have a problem with is the strength of the bowl. Mine is a thin bowl so weight tends to cause it to lean backwards ever so slightly. I also have to be careful when shifting the stand and light as it wobbles a bit. But other than that, this experiment has been successful.
Camera flash only.
Camera flash and DIY light. The colours are brighter although some of the depth is lost. The yellow cast is due to using incandescent bulbs. I didn't have any spare energy savers, so had to use these for the test. I wouldn't recommend incandescent light bulbs as they heat up very quickly, give a yellow cast and use more electricity.
And that's it! :-D
Neither of the sample photos were photoshoped, straight from my Nikon Coolpix.