Extendable cylindrical jigsaw puzzle

A cylindrical jigsaw puzzle comprising:

• a bottom rim having an outer flange, an inner flange integrally formed with the outer flange and a first gap defined between the outer flange and the inner flange;
• a top rim having a ring body, a positioning flange extending from an inner face of the ring body and a second gap defined between the ring body, the positioning flange and multiple positioning pieces formed on the positioning flange to retain the top puzzle pieces;
• top puzzle pieces each having a first assembly edge corresponding to and received in the second gap of the top rim, a first step formed on a face adjacent to the assembly edge to abut a peripheral edge of the ring body, two connection arms respectively extending from two opposed sides of the top puzzle piece and a cutout defined in a side face opposed to the side face where the assembly edge is formed to be complementary to the connection arm;
• and
• bottom puzzle pieces each having a second assembly edge corresponding to and received in the first gap of the bottom rim, a second step formed on a face adjacent to the second assembly edge to abut a peripheral edge of the outer flange, two connection arms respectively extending from two opposed sides of the bottom puzzle piece and a cutout defined in a side face opposed to the side face where the second assembly edge is formed to be complementary to the connection arm of the bottom puzzle piece, characterized in that
• each of the top puzzle pieces and of the bottom puzzle pieces has a recessed area defined in a rear side face thereof and each positioning piece has a positioning rib formed on an outer face thereof so that after the first assembly edge of the top puzzle piece is inserted into the second gap of the top rim, the positioning ribs on the positioning pieces are able to retain the top puzzle pieces.