Nice! The helmet doesn't look too small in the pictures, I think it turned out well. I gotta say that your handpainted attempt at camo turned out pretty awesome. The whole project looks outstanding.
My son uses a resin printer for 28mm and 32mm, he's pretty good at scaling already (only been at it about three months). We have yet to tackle anything in the 1:18 or 1:12 scale, but maybe this summer. The whole process seems a little daunting to me, but he is mastering it pretty quickly (he did a lot...I mean A LOT...of research before he ever even bought a printer - dozens of hours on Youtube tutorials and talking to some of the independent mini producers). We are both pretty excited about creating our own stl files, so we'll see how that goes.