I ended up making a very tough notebook—one that would sincerely hurt you if it fell on your foot.
The first section includes some different sizes of graph paper.
I made the grids in InDesign and printed the size in the bottom corner for reference. There are 1/4", 5mm, and 1cm grids.
Most of the notebook is lined pages (college ruled—wide ruled makes me crazy) and there are also blank pages interspersed for drawings or whatever.
The back cover is a piece of whiteboard. Why the bumpy overtall part? I was thinking of attaching a simple marker caddy to that section, but changed my mind.
Sidenote about whiteboard: the real stuff if pretty expensive (like $200 for a 4' × 8' board, retail), but there's a pretty good substitute available at your local home supply store for less than a tenth of that price. It will be called "showerboard," or "hardboard panel" or something else; Home Depot calls it "Thrifty White." It isn't quite as good as real whiteboard, but at $13 a sheet, it's well worth the investment.
I bought 12" plain steel piano hinges from McMaster and drilled holes where I wanted them.
End-on view of the construction. The hinge leaves to the left are hugging the paper stack. It's important that both the front and back covers can hinge, because if only the front could, it would be difficult to write on the verso (left side) pages. The paper sandwich is held together with binding posts, which are great for holding stacks of things together.
This notebook probably suffered for being too tough: it was so heavy and bulky I didn't want to carry it around when it was avoidable. Future versions will take a cue from this and trade some durability for portability. After all, if you don't have the notebook with you when you come up with the good idea, it's not doing its job! ⁂