light boxes

I am interested in what anyone knows about building light boxes for display of painted stained glass panels .... what kind of lights, placement of bulbs, diffusing material (to hide bulbs, and the "innards" of the box), dimmer switches, how one might make them portable for shows, etc.

I do some shows and get into situations where I just can't get the lighting strong enough behind my work or the bright ambient light is overpowering the light behind the panels. I occasionally have a client who doesn't have a window and needs a light box. The time has come for me to know a bit more!

Is there any company or craft person out there who has solved all these problems... maybe even makes a good looking, affordable light box that one can buy for this purpose? Or builds to suit??

Thanks, Margie