Winter is coming...and while I do not mind a cool room (I can always put on more clothing) I do dislike cold hands when working at my computer. Solutions include fingerless gloves which I find awkward and leave my fingers cold, and of course various heating devices.
Recently I came across a company selling heating pads for on the desk beneath the keyboard and mouse, and I wonder if I am able to create one myself.
This would probably be a bad idea but I find myself wondering: what if I connected a wire directly to the 230V mains? Choosing a desired wattage I can easily calculate the length and diameter needed. For example, were I to choose 20W then the resistance needed would be: $$ P=V*I \rightarrow I={P\over V}={20\over 230}\approx0.087A \ R={V\over I}={230\over 0.087}\approx 2644\Omega $$ Using omnicalculator.com (because I am lazy to write all the math) I find out that using a copper wire of 1mm diameter it would need a length of 122m, or 486 meter with a diameter of 2mm.
Why would this be a bad idea?
In the end I wound up buying a commercially available desktop heating pad.