Well, DANG! I should have thought of the steering wheel from a car made before we acquired power steering! Actually, my last race car (Lola T-394 if anyone cares) had a 12" diameter steering wheel. Even had a soft foam under a sewed-on leather cover. Great for banging your head against, without all the bruising.
Saw some nice wheel handles for dressing up a small lathe, they might work, but the company (Micro-mark???) didn't want to sell just two wheels. more like the whole package.
I have two of the pattern-makers vise, as two of my workbenches are across the room from each other. i ought to design and build a couple of those wheels, even though they need a lathe to make them.