This is a simple enough tool. I grind the tip off the end of a Harbor Freight Divider. Done! But not entirely.
There are a lot more details on my blog, but the real advantage is that you can make your own points.
This is an interesting point. Ideally you want the curve to the inside of the circle being made. The curve makes the blade try to drift outward. This is good as the circle cut mostly ignores grain and remains full sized and clean.
You might want to draw a line, make a scratch or cut deeper. To cut deeper you might want a more normal blade, but it is easy enough with a long hex drive bit and a grinder to make all sorts of cutters.