The Cig 44 kilo boat was redone in flat- but it's vinyl graphics. We couldn't tell until we were arm's length away.
Imron is available with a flattening agent that works really well. But it takes so long to set up there's no way to keep ust out of it. I tried doing a flat Imron paint job by spraying the paint and then knocking the gloss off. I tried crushed walnut, glass bead and AlOx at low PSI. There was no way to get a consistency over a large, flat area. Finally we did it by blocking it with sandpaper- it had a grain but it looked good- and it was repairable. I even tried a heavy dark base with a light topcote and then scored thru the top with 120 paper, then finished with 240. It was alot of work but it gave it a brushed metal look. No way I'd want to do a 50 Cig like that.