Take Hekkreach oil baron Hellvish Kostelloh's advice, and pump it up with this nodding donkey set. Chain not included. The pump measures 95mm in length.
 
This model is cast in Jesmonite resin and supplied unpainted. Assembly required. Whilst every care is taken to create a perfect cast, minor imperfections are occasionally encountered which may require filling etc, for these reasons this model is recommended for those with some hobby skills.