They are all old endmill holders I got with my old mill-drill or on Kijiji with other stuff. They are all VERY soft. I have a dozen or so. I don't plan to even use them as tool holders. I was thinking more like machining the holder part and then use them as centers on my 10" rotary table which has an MT3 female taper. I have a specific job in my mind for the first one. They don't even need to fit well as per the normal use of an MT3. They just need to hold center. I'll machine the end mill holder end to make standard size cylindrical centers of say 1/4, 1/2, 3/4, 1", etc. Then I'll make individual sleeves of various sizes to sit on the MT3 centre and subsequently hold the part on center on the table. For precision, I'd use an indicator but for most jobs it's easier to just use a JT3 center and a sleeve.
Way more than I need for what I have in mind.
But I never considered making a lapping tool from a form made on a known good taper. This is worthy of a formal tip in tips N tricks, and something I'll remember for "next time".
