Nice vid, CW. May I add that another reason for oscillating the lap as you demonstrate, is also to prevent grooving the lap and ruining it.
You can make laps like that with a file and a drill press or even a hand drill held in a vise. It does not have to be a full ball end. A 3/8" rod with a radiused end will work on a small caliber like .22 or 6mm. If you need to do a .45, you can bump up to a larger rod/bolt. Nice thing about a bolt, is the head gives you the size without suffering the cost of something like a piece of 1/2 brass rod.
CW, you need some soft jaws for that vise.