The pans themselves can be done with some simple rectangular channel shapes. Since they should be modeled full of water, there's not much point in doing the fiddly details of the splash guards along edges. I've tested some different Plastistruct forms and found one that fits nicely on top of Atlas C55 ties (the package is lost in the basement at the moment). Now all the associated buildings, fittings, heaters, and other yummy equipment that I need to scratch build, those would be quite nice!