In wood turning, I like inlaying some pearl dots in my pieces.
For that, the best is to manage to drill a small hole with a flat bottom.
For that purpose I once found in a shop an 8 mm bit that works very well (the white one, in the middle here below), but I can't find that kind of bit any more in other diameters, so I decided to make them :
There is a 10 on the right and a 6 mm on the left. They are made from those useless too cheap bradpoint bits like the one at the top. They are always off center and cut very badly.
So I cut them shorter, and grind two lips, at an high angle.
I leave a small centering pin.
I ground them on the metal lathe, using my Dremel attachment in the tool post, and a small cutting wheel in the Dremel.
Obviously, the high angle, and the round (not drilling) pin in the middle, do not permit to drill more than a few millimeters, but they are not actually made for drilling, but for shaping the bottom of the hole.
Works well, for what I need !