Head over to the THO Game Calls site and check out some of the tutorials. Pretty easy- drill out the blanks (3/4" and 1/2") and then turn the outsides. You can buy some grunt kits from Al on the same site.
You can turn your own mandrel from a dowel or buy a pen mandrel and expanding spacers from HUT products that will get you by. If you end up wanting to turn grunters regularly, you'll probably want to upgrade to a mandrel that will give you tighter tolerances. I bought a couple pin mandrels off of ebay and a collet chuck from PSI- money well spent!
Good Luck!
