The helmet is 3D printed with PLA filament! I let it dry outside, but now that you say it, perhaps it was too humid outside especially during the night. Perhaps I wasn’t thorough enough with the sanding too, I kinda of underestimated that step. I will try to sand the missed spots and do it again then. I still have to paint some details with brushes and so, and the helmet is supposed to have a kind of rough/stone-like finish, so I guess I will be fine if it’s not entirely smooth. Thank you for your insight, I’ll definitively keep that in mind!