Print one of everything, except for medallions based on your taste. I used support for all parts although these things will probably print without support: heat sink, cap, trigger body, medallions. The body may also print without support or may not depending on your printer. The grip and muzzle will definitely need support.
Before painting, glue the muzzle and cap into place. Now paint everything a glossy black base coat. Paint more as follows:
For the trigger body, trigger, and heat sink: use a silver topcoat.
For the combined body, muzzle and cap: mask off the parts that remain black. Since these were mostly circular I used small balls of modeling clay that I flattened enough to mask each area. Paint a silver topcoat and remove the masking.
For the grip, mask off the textured area and lightly spray with burnt sienna.
For the medallions paint lightly with a bronze metallic paint.
To assemble just glue everything together. You may pick medallions that match your preference, but they don't matter much unless your printer is very detailed. I used the PsiCorp medallions which work pretty well as a replacement for the Pachmyar logos.