30 years ago you couldn’t buy a new froe, no one made them. You could find antique ones, usually beat up and rusty beyond usability. So I made mine from old leaf springs!
the one behind is a school bus leaf spring, and the one in front is a car leaf spring. these work very well. If you want to make your own, you will need a bit of a forge to heat the spring up in enough to flatten it. And to flare out the eye a little bit (at the bottom). Do not re-harden it, it will be strong enough as is.
Today there are dozens of makers to choose from. Recently I used one from Gramercy tools. I liked it a lot.
Be careful in your selection, there are a lot of people selling “cold steel” froes and hatchets. “Cold steel” is cold rolled steel, otherwise also called mild steel. it is the softest and most malleable of the steels, and it does not harden. This is good for Tomahawks (hawks) and hatchets that you are going to use for throwing at targets. it’s not good for cutting, and in a froe it can just make you mad by bending on you when you twist it . Because you DO twist it and use it as a lever to split the wood. you want good steel or spring steel for these.
You drive the froe into the end of a bit of log with a froe club. Do not give in to the temptation of using a sledge on it. You will mushroom over the back edge that way. If you need to use a sledge, wiggle the froe back out and use an iron wedge. When the froe is in, then you twist it to propagate the split…
Split large stuff with the iron wedges and gluts (wood wedges). switch to the froes when it gets closer to the size you want.