ER25 collet block

Look, you aren't going to use this for machining and in a lot of ways this was an exercise in modeling something from a blueprint, and also i obviously can't get the surface roughness within spec.

So then what is it good for?
i had a round 8mm brass tube that i needed to thread with a die, and i just couldn't hold it tight enough in a vise to prevent it from spinning without risking marring it or crushing it.
so i did what any reasonable person would do, I spent the next day modeling and testing an er25 collet block. Does it work? No, but i suspected it wouldn't - plastic is just not strong enough to reef down hard enough.