My parents went through a phase of marbling on silk,
I think it was a 1970's thing, though maybe early 1980s?
I remember lots of messing about with trays
and oily paints floating on water (or gel?) and skewers
for trailing through the paint to create the patterns.
I wasn't very good at it but Mum & Dad were.
This was easy and quick in Corel's free trial of Painter
but the original file's pretty big, 11.8MB,
the computer did all the hard work!