See http://www.appropedia.org/Adjustable_Bike_Mirror for full printing and assembly instructions
Mount the two clamps onto the bike handlebars using two zip ties. Using the adhesive that came on the mirror ( I used a blind spot mirror for a car that you can pick up for $1 at Walmart such as this one ), or using superglue, attach the mirror to the flat part of the base. Put the balls from the rod and base into the appropriate sockets of the mount and find a position with the rod and base that suit your liking, then remove the balls and apply some super glue to them. Reinsert the balls into the sockets and allow to dry. (I find that gluing the balls in the sockets may or may not be necessary, depending on the tolerances of the printer.
Pay attention to the orientation of how the parts are printed in the photos below. For the top clamp, make sure to use supports and print it so that the joint is on on the side, this maximizes the strength of the socket. For the rod make sure NOT to use supports and print it ball side UP (socket faces down).
Rod: 50% infill, 0.2mm layer height, print with the ball up, no supports. If your printer has difficulties with printing this for some reason, use a small raft.
Base: 15% infill, 0.2mm layer height
Top Clamp: 50% infill, 0.2mm layer height. Print with supports and the joint on the side as shown in photos below.
Bottom Clamp: 25% infill, 0.2mm layer height