Die Puzzle

The author of Thing 31685 mentioned it was inspired by a circa 1893 puzzle book, which led me to read that book online. There, I stumbled on the "Spots" puzzle, http://archive.org/stream/puzzlesoldnew00hoff#page/98/mode/1up , in which an oversized die is cut into nine simple blocks. The surprisingly difficult problem is to reassemble the die.
My version takes advantage of the fact that 3D printing can easily build more complex shapes. First, the dots are not merely painted, but are conical hollows. Second, rather than having the internal edges be simple cuts, I have introduced an interlocking pattern of conical hollows and bumps. This makes the assembled die hold together somewhat, but the puzzle is at least as difficult to solve because the internal and external hollows look identical -- I even painted them identically.
I also made the die face pattern match the modern dice I had at home. All dice have opposing faces sum to 7, but the book's face pattern is slightly different from