

Did you try FreeCAD after v1.0 release? I heard it got more intuitive with the release. I would prefer to stick to FOSS tools, and Fusion360 does also not seem to have a native Linux version?
But yeah, it is the impression I have gotten that FreeCAD is not very easy to get started with and why I thought to stick with what I know (Blender) for my first project.
ETA: Hm, how thick do you think the walls would have to be?
Oh, that could be a much better solution. How would you design the reservoir filling system in that case? It would be difficult accessing the rear reservoirs directly, but I could maybe make something with cheap PVC-pipes. Ideally I would fill it from only one point, and I eventually plan to have some sensors measuring the water level in the reservoir(s)