Assemble buttstock (may have internal spacers). Attach pistol grip below receiver.
Fold bipod legs into V-shapes. Attach mount to front of receiver. gpm paper model
If box magazine: fold as a rectangular box, attach under receiver. If belt-fed: create dummy belt links (optional). Assemble buttstock (may have internal spacers)
Fold and glue rear sight (flip-up optional). Attach front sight to barrel. Glue carrying handle to top. gpm paper model
Fold and glue the left and right receiver halves. Reinforce internal edges with small tabs.
Roll the barrel into a tight tube. Wrap the cooling jacket (with holes or slots) around it. Attach to receiver.