[rodneym]

Have you been to an upholstery shop?
You'd be best off with a vinyl with a woven or supported backing, not unsupported (no backing) or a non-woven backing, which is like felt and won't grab well.
Tolex brand vinyl (google it) is used for covering amplifiers and is a good quality vinyl.
Follow the Weldwood directions carefully. The vinyl against the metal won't breathe and you don't want to soften the vinyl too much. Allow a few minutes drying time on each side before laying it on.