In this "version #2" on the same topic, I found more photos for the '1/2-round burs'.
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These special burs cannot be found ready-made for you in any tool supplier. YOU MUST CREATE THESE YOURSELF, SORRY!
This is a rough hand drawing showing the basic instructions.
While holding the rotating bur in your fingers, if you feel any slightest amount of heat...STOP and drop the hot bur into a beaker of cold water. These are signs that the bur is getting softened and becoming useless.
In this rough drawing, is what is happening as the final result will be a fantastic Cabochon-shaped cutting bur.