The following is a quick test of my light box that I made using the box from a 17" computer monitor and some translucent white garbage bags (and my new Nikon D60). I just chucked in these three things to test it out and it seems to work fine enough. I think it is gonna be even better with a few minor adjustments.
If you're going for isolated-on-white product shots, you need to get more light in there and it needs to be more even.
There's a pronounced gradient with the top of the background being much lighter than the bottom; the shadows are also fairly obvious too, so you probably want more diffusion.
(Not that I'm claiming to be an expert - I've found exactly the same problems doing similar shots. Properly lighting isolated product shots is a serious pain...)
I agree with ganders - if stock photography is your goal, then you need more light, better diffused. My first impression is that the clarity of your test images are not yet good enough for the more popular stock sites. This is just because of the quality of your light, in my experience. Keep experimenting with the light box - the more sides you can cut out and replace with diffusing material, the better.
I made one myself with just a cardboard box and tracing paper, and it works pretty darn well with my SB-600 Speedlight.
I see what you were saying. I put another (more milky and less transparent layer of plastic over the previous windows and this is what I came up with for a quick test.
I think it is LOTS better. You?
I think with some tweaking I will get there with my cardboard light box.
