If you don't trust your own welding (like myself, also an amateur welder), then a tip: After checking square, tack weld each corner before going in and fully welding them. This way, you can mitigate the risk of overheating and bending things out of square while fully welding the corners.
You should fully tack the entire table in this instance, checking squareness in each stage. After it’s all tacked then fully weld it. Helps prevent distortion etc.
whats the thickness of that metal plate, when beaing supported by a mdf board? just curious, if it could be as little as like 1,5 - 2 mm and still being quite stiff
