Jeez.. when I wondered how people did it I guess I just over thought it. My mind went to a big underground criminal ring in China where they made their own false dies to make counterfeit errors and sell them as legitimate... Not the first time I've overcomplicated things, just ask my wife, lol
Nah, by the time I got done trying to get a cherry-red-hot steel rod positioned in the vise (no matter its orientation), I would've surely set the garage on fire, and probably burned some holes in myself as well. Thinking about clamping the rod securely, getting the TOP end hot, then putting a coin on it and quickly slamming it with a sledgehammer. I still probably won't get up the nerve.
I can see where that could be a problem for some. Take the rod and lock it into the chuck of your drill press. Lift the drill press table up to a height where a turn or two of the handle causes the rod to make contact with the table. Align the coin on the table at the point of contact. Secure the coin onto the table at the point of contact using a drop of wax. With the drill press in the raised position and the steel rod still secured in the chuck - heat the end/tip of the steel rod to cherry red. Please note do not heat the end/tip of the rod secured in the chuck. Heat the opposite end. Once cherry red turn the drill press handle until an impression of the coin is transferred into the tip of rod.
That all seems fairly practical, except that my only drill press is Dremel-scale. The "things you already have around the house" constraint is causing me some embarrassment here...