I'd like to build my own heat bed with nichrome wire. However, instead of using the 12v power from my power supply, I'd like to use a relay switch powering from mains 110VAC. I was thinking of using a signal from my arduino to control the relay once ideal temperature is reached.
Here are my questions: how much nichrome wire should I use, and what gauge? Is it as easy as clamping down the wire and using kapton tape to heat the aluminum bed? (Please note that the temperatures I'll need it for shouldn't exceed 200 Celsius.) What's the cheapest way to achieve this (preferrably without having to buy power supplies, or adapters/transformers).
PS. how do soldering irons work? are they just steel rods with a buch of low resistance wires inside, or do they use transformers to drop down mains voltage? Maybe I can copy how soldering irons work..