In economics, putty-putty describes an attribute of capital in financial models. Putty-putty capital can be transformed from flexible capital into durable goods then back again. This contrasts with putty-clay capital which can be converted from flexible capital into durable goods but which cannot then be converted back into re-investable capital.
References
Further reading Atkeson, Andrew; Kehoe, Patrick J (September 1999). "Models of Energy Use: Putty-Putty Versus Putty-Clay". American Economic Review. 89 (4): 1028–1043. doi:10.1257/aer.89.4.1028.