What is Reddit's opinion of PTC Car Fan Air Heater, 100W 12V Energy Saving Constant Temperature Heating Element Heaters for Heater Humidifier Air Conditioning Appliances?

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seen these? I'm in a similar boat where it's usually sunny and not overly cold during daytime.

https://smile.amazon.com/dp/B07MDN81C3/ref=cm_sw_r_cp_apa_fabt1_g6BVFbE1P4CDJ

I'm going to use one of these, aiming it towards some rocks bound up by chicken wire. Going with an arduino controller to turn it on based on temperature.

I used this design with some modifications: https://www.thingiverse.com/thing:4356645 With this PTC heater: https://www.amazon.com/dp/B07MDN81C3/ And this controller: https://www.amazon.com/dp/B07K68JJY1/