Patience of a Saint and extremely skillful!!!
OPERATIONAL V-12 ENGINE THAT FITS IN THE PALM OF YOUR HAND.
This is not CNC technology; this guy made everything at home on his lathe and drill press. Took 1220 hours (a year and a half?) to make the 261 pieces. Note the end-loaded crankshaft into the block (like an Offy), 12 individual cylinder heads, TINY rods and pistons, dual "underhead" cams with push-rods to rockers in the heads. And, he did break-in using an electric drill driving the crankshaft!
Even if you're not an engineer, you'll love this!
Click Here to view.
Source: Internet