Here's what you'll need:
- Wood veneer. You'll want this relatively thin- probably any normal, commercially produced stuff is OK.
- A custom stamp. I ordered mine through Fedex/kinko's online store, but I'm sure others are just as good. This will cost around $10-$20. If I could do it again, I'd make the font a bit bigger and less complex.
- Measuring tools. A decent ruler is nice, as is a square. So long as your blanks end up smaller than the normal card size (3.5"x2.0" here in the US), it's not terribly important that the shape be perfect. A bit smaller or a bit trapezoidal is perfectly fine.
- A good, sharp knife. I used a nice, new blade in my utility knife, one of the extra fancy bi-metal blades that Home Despot sells. I'm not sure if it makes much of a difference versus the regular kind, though.
Step 1: Make the Blanks
If the grain's not perfectly in line with your rip cut, the blade can get caught following the grain, not the straightedge. Splitting wood is seductively easy- don't go too fast, or you might deviate from the cut. You should also align the straightedge so the grain will push the blade towards the guide, not away. I like to keep the knife up at a relatively sharp angle, and cut clean through in one pass. Quite easy, once you get the hang of it. Use these rip cuts to split the wood into long 2 inch strips, which can then be split into individual cards.
When cutting across the grain (or on burled/figured wood, where the grain is wonky), you need to beware applying too much pressure and cracking or breaking the wood. I like to hold the knife blade relatively flat (small angle against the wood), and try to score the surface once or twice. Since you're only cutting two inches across, it's then quite easy to snap through the remaining material cleanly.
Step 2: Stamp and Seal!
Once the ink is dry, I hit it with some varnish, to bring out the color of the wood and protect the ink from smudging. I used spray urethane from a can- I feared that varnish (which often contains solvents and/or oils) would smear the ink if I used a regular wipe-able or brush-able formula.
Step 3: Final Thoughts
The cards are rather robust, but are still somewhat susceptible to breaking. If this concerns you, you might try encasing them in epoxy to make them stronger- I don't think it's a big deal, though.
If you've got access to CNC equipment, you might try making your own brass branding iron, to burn your name into the wood. I think that would be pretty awesome, but requires more technical skills and labor. You might also buy one from lee valley (http://www.leevalley.com/US/wood/page.aspx?cat=1,41115&p=44057), but I don't think they offer enough lines of text to be suitable.
Some veneer can be warped or bendy; you can buy special products that soften the wood, and then press them with a pile of books to get them back flat.