The rose engine, a specific subset of the family of ornamental lathes, is essentially a spirograph for metal. Here, a machinist carves a repeating offset pattern into a brass slug the size of a dime.
The superset of full ornamental lathes are essentially /three-dimensional/ spirographs. Here's an artisan using one as part of making an egg full of eyes (footnote 1).
(1) I know my audience. n.n
@Momentrabbit Being sometimes a brass device myself, I can't help but find this fascinating. And more than a bit lewd. Nicely done.
@Momentrabbit *oh my goodness gracious*.
Yes. That's. Eeee. <3