My bag of cement (wrongly called it concrete in past posts, I am not adding sand to it so technically not concrete) is arriving tomorrow so in preparation I have printed the parts that I will need, the encoder coupler (printed twice because it was too loose), the bottom disk with the blank shape of the coupler on it and currently being printed, is the flat top disk and one more part which is an outer ring to fit outside the PVC sheet to sandwich it to the bottom disk to help it hold its shape, and hopefully squeeze the sheet as close to the bottom disk as possible to prevent water leaking out.