I need to make/buy an extension cord for a welder. 50 amp 250 volt. Nema 6-50R.

I want this to be to code, so no recept mounted in a 1900 box at the end of a cord.

Searched a number of different catalogs online and cannot find a female cord cap for that nema number.

Anyone have any idea where I can buy one?

Or even if they make pre made cords?

The welder guy wants an ext cord but if I cannot find a cord cap I will simply put a longer cord on the welder. Male cord caps are easy to find. It currently has a 8 ft cord.

Would putting a longer cord on the welder be a code violation? UL violation?

If that does not work the last option is to put more hard wired recepts where he needs them.

The welder guy wants to be able to roll the wire feed welder around his shop to wherever he needs it. This is a big shop about 50 ft square.

Many thanks.