thanks guys with the feedback. MOT stands for Microwave Oven Transformer, hobbyist use it to weld battery tabs.
The 5mm is actually the width, i was referring to the weight of the copper like how many ounce ? if could get that i could check with some ebay sellers.
Yes the traces will be covered with solder mask and a few cutouts too will be made. My AC mains are rated at 240Vac.