That drill press rattled my brain for a few minutes there until I decided to look up the mechanics of it when I couldn't figure it out... Neat !! I never would have thought of that.
The only other thing I can think of would be one of those round hacksaw blades but I don't know if it would cut evenly on something 5" thick.
Sorry, I mis-read your post slightly when I relplied...you're talking shape and I'm talking size...maybe I gotta make some coffee. But I guess my main point is still sorta on topic :)
One thing that is better than commercially available is easy-to-make...I don't mean to say that if it's not easy it's not worth the work...But if it takes half the time to make a nice fitting tool most people would be more inclined to make their own, with a 1/2" hardy hole you could make tools to fit it quicker and with greater ease.
Not sure about the type of steel...but a big chisel like is nice for keeping your hand away from the heat.
The first few that I made were much too short to use comfortably with hot steel.
Thought this would make a nifty Father's Day gift...for those super hard to open bottles...Dad's a farmer so he likes things extra heavy
Pretty high carbon from a flat bar with a hole in it, found it out in the field. Ended up being over 9 1/2 " long once finished.
I had to test it on a twist-off
You could use basically any scrap depending on the size you want, although coil spring, torsion bars, equipment shafts, sucker rod, and car axles would probably work fine and can be found in a variety if lengths and thicknesses.