Puzzle pen

A puzzle pen comprising a penholder holding a writing member for writing, said penholder comprising:

• a shaft;
• a plurality of puzzle rings respectively sleeved onto said shaft and abutted one against another, said puzzle rings each comprising a body, said body having a plurality of locating grooves spaced around the periphery thereof and extending through top and bottom sides thereof, and a plurality of puzzle blocks respectively coupled to said locating grooves;
• and
• a retaining device mounted on one end of said shaft to hold down said puzzle rings against one another, said retaining device comprising (a) a locating ring axially movably mounted on said shaft, said locating ring having at least one receiving groove respectively formed on the periphery thereof and extending through top and bottom sides thereof for receiving one puzzle block of said puzzle rings, (b) a cover shell rotatably mounted on said shaft and covering said locating ring to keep said at least one receiving groove of said locating ring from sight, said cover shell having a side opening for allowing one receiving groove of said locating ring to be exposed to the outside for receiving one puzzle block of said puzzle rings when said cover shell is rotated on said shaft relative to said locating ring through an angle to align said side opening with the receiving groove of said locating ring, and (c) a spring member mounted around said shaft and between said locating ring and said cover shell to force said locating ring against said puzzle rings.