You'll need scissors, tape, glue, markers, a hole punch, tweezers or needle nose pliers, a brad, two paperclips, two drinking straws and the robot PDF. (The original template came from PaperBotz, a most excellent site. I edited it in GIMP.)
Cut out the robot and punch holes on the black and gray dots. If you don't have holepunch, just place the cardstock on a mouse pad and use a ball point pen to punch a hole. Carefully fold on all the solid black lines. (It can help to use a ballpoint pen over the lines to score them and make it easier to fold.)
Use transparent tape, double-sided tape or glue to assemble the two pieces of the robot. Leave the front of the body open and the back of the head open for now.
Before completing the head, put a brad through the gray dot. Then seal it up. (You may want to gently bend the arms so that it doesn't fall back into the head.) Insert the bottom of the brad, now attached to the head, into the hole on top of the body and and spread the arms of the brad to attach them. This can be harder to do than you might imagine. Use tweezers to pull the arms of the brad into the body.
Then take two drinking straws, the bendy kind, and cut them in half. On the half left with the bend, remove another inch, to shorten what will be the arms. On the top of the straws make two slits downwards. Insert the two pieces with the bends into the arm holes, spread the cut straw and tape into place. Repeat with the legs, then seal up body. Now add whatever bling you like. I'm a big fan of googly eyes, personally.
To make feet, take a paper clip and unfold it into an "L" shape. Push one end into the leftover inch of straw from the arms and the other into the the leg. Repeat for the other leg. Voila! Robot!
Obviously, for a quicker version you can just tape the head onto the body and slide the straws into the hole without securing. It's just as much fun, but won't last as long. Or, if you want to be super cool, Bend the leads on a blinky LED at 90 degrees, attach the leads to a coin battery and secure with tape. Punch a hole in the top of Mr. Roboto's head, insert the LED through the hole and tape the battery to the inside of the head. No he'll light up!