It's such a steep learning curve this 3D stuff.
Trying to do the raised, "cast" bits of the engine cover. I've printed most of the bits but found that because of the way the printer lays down the extrusion you are left with a perimeter border and a pattern on the top of the print. Sanding it doesn't remove this as it's the structure of the print so I'm going to try using paint as a filler, ie take most of it back off, to try and give a smooth, pattternless surface. It seems to work on small bits so here's hopping.