Several of the Carnival Glass clubs have had Fenton and other makers devise pieces (or sets) for sale at their conventions. There is quite a secondary market for these pieces. Here are several lists of them.
Bells for HOACGA, Fenton
American Carnival Glass Association souvenirs
International Carnival Glass Association souvenirs
Woodsland World Wide souvenirs
Holmes County Antique Festival
Encore for Dorothy Taylor
Texas Carnival Glass Club