Cars, even cars that no longer work, are still massive collections of interesting, well-engineered mechanisms. They're like massive collections of great parts just waiting to be used. And that's exactly what Tom Jennings did when he needed an X-Acto blade handle.
Why go to Office Depot and buy some plastic-and-crap handle when an old Rambler Six engine is full of beautiful steel pushrods? Tom happened to have an old Rambler engine, and took a pushrod and machined a little 0.10" undercut to align the blade and a 0.20" little step to keep the clamping plate aligned.
The end result is a very positive grip on the blade, and an X-Acto knife handle that should last until we're all brains in jars, and have evolved past the need to make precision cuts.
(Full disclosure: Tom's a friend and was on the Make:Way Lemons race team with me. He's knows a crapload about Ramblers and AMCs, too.)