Your photos look good. I have friend that is a professional photographer and he has given me a few tips on lighting.
1) Your tent should be made out of white "rip-stop nylon" because it diffuses the light to minimize reflections. You can get the material at any fabric store.
2) See if your camera has a custom white balance. If it does, take a picture of the background only without any products. Go into your custome white balance and select the picture you took. This is telling your camera that what it sees in the picture is "white".
Great pics. Like what was mentioned above, you want to use something else besides tissue paper, you know, the flame thingy. The tents really bring up taking pics a couple notches. BTW, your pens are nice to. Carl
Excellent results from a ghetto tent, while other materials like rip stop nylon will be more durable than your tissue paper, I doubt anyone would be able to tell the difference from the photos if you switched. The stuff is really cheap though (I got some for under $2 a yard), so it might be worth picking some up if you happen to be near a cloth store.
I suspect however that using rip stop nylon on a soda can box would be a bit silly! Maybe if you do larger turnings and got a bigger box it would be more worthwhile.