Since Kludge had posted a couple of acorns, I decided to try my hand at 'em too...I quite like them, and they weren't so bad to make one I figured out a process that doesn't require removing anything from the lathe...
Drill chuck and forstner bits, Peter - I can't believe i tried to hollow out the first one with a bowl gouge...
Once it's hollow, the rest is easy! I found that a sharp forstner to make the bird-entry-hole is important too - a few wanderers resulted in a lot of extra work!