Large Delta printer build - advice and suggestions welcome

[AutoWiz]

You can actually use a solenoid relay, it uses what's sometimes called Bang-Bang control rather than a PID loop with PWM. It basically involves turning the heater fully on and switching it off as it approaches the target temperature, then switching it on as the temperature drops. It's a lot cruder and the temperature is less stable since the heater is either off or going full tilt, you can't turn it on just a little for fine adjustment. It is usable if you're on a tight budget like OP says they are, but they're also wanting to use profiled linear rails so that's sending some mixed messages.

So for those who understand electronics when we energize a coil and then release the power what we get is a serious voltage spike. This effect is called a "collapsing field" and it is the stored energy in the windings of the coil quickly searching for a path to ground. It is also how spark plugs get their power to bridge an air gap in an engine's combustion chamber. It's how we can achieve Kv from 12v. By energizing a coil and then releasing the ground. And that collapsing field can generate so much power it can jump an air gap, or arc through plastic or an ignition wire if it needs to but that spike is so powerful it will find ground. To PWM or otherwise rapidly switch power to a coil is to constantly and repeatedly in fast or even a less fast fashion apply this affect to the controlling circuit. And it won't live long. We don't PWM solenoids or relays with coils. Solid State Relays ONLY for PWM, pal.