I came across this a week or so ago - another thing found on Behance if I remember correctly, and I’ve had a bit of a play around with it. I like the idea of a Fontstruct-style system for Blackletter, and I can see that Jan Schöttler has created some quite lovely things with it, but without looking at the PDF in Illustrator I would find it far, far easier to draw the letters with a pen and brush than make them with this kit. It reminds me of a Tangram puzzle game in a way. I had a play around with it and created the word below, which is tending a bit too much towards the death-metal band logo for my tastes, but hey, it has a bit of charm. Maybe you will have a better experience with it (warning, Flash site).
Update: Jan Schöttler emailed me to say that he didn’t do CombineBox alone, and that it was Andre Apel‘s Master-Thesis at the HFG Zürich.