@wendy I just designed a little dummy cell for testing a new potentiostat design which we are currently developing. It would work with the Cheapstat as well. I've ordered 10 PCBs - which should arrive in about two weeks. I could send you one if you would like.
Dummy cell schematic
Dummy Cell Layout
You could put different values in for R1, R2, R3 and C1 for different tests.