Well, this can go rather wrongly, I hope I didn't push the editing limits too far...
This is an 80 seconds exposure in a dark room. In front of the glass there is a black cardboard, split in half. With the camera in bulb mode, I lifted one part of the cardboard and triggered the flash.
I then covered everything, filled the glass, and lifted the other half of the card. Triggered the flash again.
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Hmmm. A shot cleverly done, but to me the subject is a glass with blue stuff in and this is a photo of the full subject. I'm probably being ultra-picky but I'm feeling this isn't quite what the challenge is aiming for. Therefore I'm knocking a couple of points off for my perception that this doesn't quite meet the challenge.