This is such a great activity to strengthen fine motor skills.  I cut out two worm shape pieces from a cardboard box. I then let my boys decorate the worms and glue on googly eyes. 

They uses Sharpies to color but regular markers work just fine.  Once they colored their worms I just simply had them clip on paper clips.  I let them put the paper clips on any way they wanted as long as it was attached!