This page is mostly a copy of my Thingiverse entry here, but with extra observations: http://www.thingiverse.com/thing:25772Before paper was commonplace, the method for keeping your thoughts in order was the wax tablet.
They're surprisingly easy to write on, and are capable of capturing almost the same level of detail as pen and paper. If you make a mistake you can use your finger or the rounded end of your stylus and smooth the wax back to blank again.
There are three designs here,
*a pocket 3 leaf version with spots for 4 'pages', (lasercut)
*a large single tablet version for a notebook (CNC milled)
*a single page one reminiscent of modern technology. (lasercut)
Here's some more information on wax tablets:
This is a useful guide to making and using tablets: http://www.cs.vassar.edu/~capriest/tablets.html
1. Cut all the layers in your wood of choice and glue with PVA glue. If the wood surface is too smooth on the bottom you might have trouble with the wax not sticking to it. Milled pine worked for me, but lasercut ply was too smooth. Roughen it up with a sharp tool if you need to. Basically don't sand it.
2. Get the wax and colourant you're going to use. Darker colours work better as they provide the most contrast. I used a plain white candle from my local $2 shop, and a couple of jumbo crayons (purple, black, green and blue) mixed together until I was happy with the various colours.
3. Heat the wax in a metal pot. Some people use a double boiler to avoid overheating, but I used a hot air gun carefully and was happy with it. Just be really careful not to boil or bubble the wax and mix it thoroughly.
4. Start pouring the wax into the tablet. Pour only just enough to fill the base layer or less. I filled mine until about 75% of the wood was covered, then tilted the tablet to overcome surface tension and fill the rest. That way when the wax is cooled the surface will be a little below that of the wood, and unlikely to abrade away in your pocket, etc.
5. Let it cool for a few minutes. If there's too much wax in there you can scrape off the excess with a flat bit of wood across the top surface.
6. Let the wax cool thoroughly all the way through (might take half an hour or so). Then you can rub the top surface with a cloth or the rounded end of a stylus. This is also how you erase your tablet when it's full. (You don't really need to heat it to erase stuff. If it's in a really bad condition you can, though).
For a stylus, I've found an ordinary ball point pen works pretty well. I've got a four-colour one, and devoted the green colour to wax, so I don't have to carry a separate device to use the tablet.
Lots of luck, love to see photos if anyone makes their own!