To bake round/tube/shaped Gingerbread pieces, what I do is find a metal tin the size of what the tube/tower/trunk should be (in diameter). I measure this tin to figure out how large the piece should be, if laid flat, to wrap around this tin (you can practice by wrapping the tin with paper and measuring the paper). I then cut out the dough based on this flat piece.
I bake the piece (still flat, baking it on foil). As soon as the piece is done baking, I let it cool for about a minute or two (just cool enough to handle) I then drape it around the metal tin (or something round) to finish cooling (foil and baked dough). When the piece is totally cool, I removed from the tin (sliding the tin out from the middle) and carefully removed the foil from the inside.
This works better for me than actually baking the gingerbread piece ON the metal tin - due to the gingerbread dripping off the form. Since the dough is still very pliable after removing from the oven, this method of draping over a "shape" AFTER baking seems to work well.
Sorry I don't have pictures of this process... I will get some loaded as soon as I can.
Below is a sample of the tube-shaped gingerbread pieces I made.
