IMHO, the problem you are having is not a shadow. The black areas of the Pen are very glossy and are simply reflecting your tent and background/foreground. They area you refer to as shadow is the gap in your tent.
There are a numer of ways to eliminate that.
1. you could use a "roof"---build a panel to simply go over the two sides you have now. You can light through this too. This is called a separation light in the commerical photography world and a "hair light" in the portrait.
You can similarly build aonther panel for your tent with a hole in it for the lens, to shoot through to give yourself "Cleaner highlights".
Remember that you are photographing the reflections when you have a glossy surface. The most difficult thing I have ever photographed was a mirror. For a mirror you must plan the reflection. Same thing here. The easiest way to eliminate some of the reflections is too not use white on a black reflective surface. It will turn what should be black to gray. Backrounds for pens are easy---mostly because pens are small. You can go to Michaels or hobby lobby and have a new background for .50 (Cheap poster board. The cheaper-thinner the better)
Some of the other guys I see have used black glass, polished rock etc...this can ease some of your problems as well as look very attractive. (the polish rock hides shadows very well.) And the separation light previously mentioned really makes highlights pop.
Also, don't discount the hot lights so fast...if your strobes do not have modeling lights or even better modeling lights that are balanced/coupled for the power output, it is more difficult. Now days with digital you can balance color really easily either in camera or in a manipulative software. Thus making hot lights more attractive.
Having said all that, your photographs are very nice, with a few small improvements they can be exceptional.
Feel free to PM if you want, after being a Photographer 33 years, I feel I can help.
Mike aka: Moke
