I’ve bought the 10kw rounded heater elements (https://store.brewpi.com/mashing/stainl … ter-10000w)
and a three phased Solid state relay (https://store.brewpi.com/temperature-co … ay-ssr-20a)
and PID controllere (https://www.amazon.com/gp/product/B0195V53X8/).
Is there schematics for how I assemble these into a controller box anywhere? Where what wires go and such?
For the electrical connections to the element, please refer to this guide:
Each loop will have 1 leg on neutral and the other on a phase.
Your SSR will switch the 3 phase wires and will be controlled by the PID.
Power in to A1, B1, C1 and A2, B2 and C2 to the element. The neutral and ground is not switched by the SSR.
The control signal from the PID can be optionally interrupted by a float switch to prevent turning on the element when it is not submerged.
You should put a link to this one in your store
How do I integrate the float switch into the system? I bought the dual float switch so that it would automatically turn off the pid controller once the water level is below the temperature sensor, but to be honest I am completely lost in terms of where am I supposed to connect the float switch’s wires.
Can anyone help? 
Let it interrupt the control signal to the SSR that switches the heating element. Just put between the spark and the SSR, preferably in the signal + line.
That way it is a hardware safety check that doesn’t depend on anything else.