reply to u/NoFace125 at https://www.reddit.com/r/typewriters/comments/1vb701u/thoughts_on_3d_printed_parts_on_typewriters/
I've heard mixed things on 3-D printed platens and there aren't many out there from what I've seen/heard.
I've seen lots of broken spacebars, though never run across a 3-D printed one.
As for the platen knobs on the Hermes 3000, they're probably one of the most commonly broken parts of any typewriter out there, and I've seen dozens of variations of printed knobs for those. It's almost like you don't own a real Hermes 3000 unless you've replaced the knobs on it.