Some wood, some oil and some tooling and you can be done in no time.
*not so useful for e-books, not there's anything wrong with e-books.
Step 1: Materials and Tools
Drill or Drill Press
Forstner bits. A type of drill bit. You might be able to make do with standard twist bits but the forstner bits allow you to easily and safely drill overlapping holes which is nice for making an oval thumb hole.
Sand paper of various grits
Dremel with sanding bits: (optional but SO useful. a bench sander would be helpful for the outside curve but the inside curves would be problematic.)
Some paper and pencil.
Olive or mineral oil.
Step 2: Design
The hardest part or this step is cutting out the thumb hole. it's fairly small. take this time to get it roughly the right size for your thumb by unfolding, trying it on, and then cut out a little more until it's big enough. You cant make the hole smaller butg you can drill a smaller hole in the wood later so don't stress. Just get it close.
Step 3: Trace
Step 4: Drill Baby Drill
Clamp down the wood and get drilling. I started with one side of the oval hole and then did the other. If you want a bigger hole you can use a larger bit and do the middle first, then do the sides with the same or a smaller bit. Whatever your strategy I highly recommend the Forstner bits they have no problem overlapping holes even if all you have is a hand drill. You shouldn't even try overlapping with a twist bit if you don't have a drill press and even then it'd be difficult.
Once you have the hole drilled try it out on your thumb. If you want it bigger go ahead and do that now. In this case it had the fit I wanted but I discovered later that it's more comfortable if your knuckle fits through the hole.
Step 5: Cut It Out
Step 6: Sanding
Once that's done you should round the edges, both on the outside edges and especially around the thumb hole. It looks better, is more comfortable, and prevents splinters.
Next you want to sand down the whole thing really well with successively finer grits until it's nice and smooth. The finer you go the smoother it is. I went down to 220 grit which is plenty smooth in my opinion.
Step 7: Rub It Down
Using a cloth or paper towels thoroughly oil it down. Oiling 'hydrates' the wood keeping it from splitting and makes it a little smoother. It also darkens the wood and brings out the grain.
I used olive oil. It works great but imparts a slightly yellow tint you wouldn't get otherwise. Mineral oil is what most people use and since it's colorless you won't get any tinting you didn't expect.
Once it has bee thoroughly oiled you want to buff it down with a clean, dry cloth or paper towel. This takes off any excess oil.
I would then wait overnight or a day for everything to soak in and repeat the oiling process.
Make sure you wait a bit and get any excess oil off before you stick it in a book. No one wants grease marks on their pages.
Step 8: Final Thoughts.
This isn't a difficult project so try one and if you want to change the design it's easy to make another one.
Some things I learned:
I found it more comfortable to have hole large enough to get my knuckle through, just make sure itsa lso big enough to get your knuckle out of again. (A lesson I thankfully did not have to learn the hard way.)
Olive oil does the job nicely but subsequent ones I used mineral oil so they wouldn't turn out yellow.
Plywood is fine and I kind of like the look of the edge once it's finished but the thin layers of ply can chip at the corners ruining those nicely sanded edges. So I would use solid wood. you can get hardwood in half inch thick "craft boards" at the hardware store. And that seems to be the perfect thickness. just be careful that most lumber marked half-inch is actually less than that.
Makes an excellent gift.
Try drilling an extra hole close to one end and threading a string or ribbon through it to use as a bookmark. Double the uses!