We don't have synonyms for riglet yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are piglet, ringlet and aiglet.
(n) :
(printing) rare spelling of reglet [(printing) A strip of wood or metal of the height of a quadrat, used for regulating the space between pages in a chase, and also for spacing out title pages and other open matter.]
(n) :
(printing) rare spelling of reglet [(printing) A strip of wood or metal of the height of a quadrat, used for regulating the space between pages in a chase, and also for spacing out title pages and other open matter.]