Parts were smoothed with drywall spackle, lots of filler primer, and painted. Individual parts were welded (melted) together using what is essentially a soldering iron with a flat tip many parts were too thin for any kind of joints or fixtures to be practical. Most of the parts were printed at 0.46 mm layer height.
Printed an entire suit of enormous Fallout power armor on his Monoprice Maker Select 3D printer, which took some 140 days and over 120 pounds of IC3D PLA filament. Happily, was able to arrange a sponsorship with IC3D for the build – who would be crazy enough to use so much filament over so long for an entire 7+ foot tall suit, right? Over those 140 days, the belts on the printer needed to be replaced twice but it otherwise chugged right along.