I have something, the only photos I have to hand are my first attempt - it was gaming terrain rather than fins scale modelling however with a bit of practice I got it down to something reasonable on my models as well.
For context - I was converting some simple cans into "tanks / silos" that were then heavily weathered.
My philosophy when making terrain / dioramas is that if someone can obviously see what it's made from, it's not good enough!
A few key points from my attempts;
1. roll out milliput on a CLEAN surface- making such thin rolls it will pick up any dust or contamination and be difficult to apply. Also, make sure the rolls are uniform.
2. I found making a slight seam for the roll of milliput to "sit" into makes it so much easier, thin sausages of the stuff have a mind of their own! (ok, so the gaps in my photos are a bit big, but the end result was ok-ish for what I was trying)
3. Don't press too hard, (some of my example a bit too pronounced) - it doesn't take much to "suggest" the weld beads. Also, I found it a bit easier when the milliput had started to cure so that it wasn't as soft.
4. The milliput can be smoothed before it sures with an old water-damp brush to smooth it a bit - very useful to get different effect.
5. I used home made tools - very easy to make and modify to suit what works.
Those in the photo are obviously old paintbrushes.
i. Remove bristles flush with end of ferrule
ii. Scoop out bristles / glue with a drill bit or similar to 1-2mm deep (don't need more)
iii. File end to angle that works
iv. Polish and smooth off metal (2000 grit + cloth and polish compound or buffing pad) - important so that there arn't marks transferred to the milliput.
Since the brush has a chromed brass ferrule, it is really easy to shape because it's soft. Comes ready with a handle fitted!
Alternatively, most people have brass tubes etc. handy - however these may need the end thinning a bit to give a soft edge rather than the blunt end of a cylinder.