Recently tried this setup with easy to get materials and only one external flash. I used my Mont Blanc Starwalker as model.
Effect came out to be rather good. Of course post-processing is still necessary.
The clear folder box is lifted up, using a piece of normal printing paper as backdrop. Flash was placed below the folder at a 45 degrees angle. Fine adjustments were made to have the proper background gradient behind the bottle.
The effect would be better if flash was placed further down and further back from the object. But that was not possible due to space limit.
