I have been thinking about getting that book. It does look bit fiddly to make.
David, go for it! Just make certain when you cut the slots, cut them too small. You can always sand a little more off, but I haven't figured out how to put it back on yet!

Also, I ordered some 1/8" number/letter stamps to mark the slots where they fit together. The patterns are clearly marked as to which slots are what, and once I finished cutting a piece and peeled the pattern off, I used the pattern as a reference to mark the slots with the stamps. After sanding everything, treating with BLO/MS actually caused the stamped numbers to have a little more contrast, making them easier to read.
Like I said, go for it. It was fun!