I've built several. Usually use 1/4" wall.
Where a problem appears is if you try to use normal square tubing to make the female part.
Correct tube is OD dimensions. Pipe is the ID dimensions.Isn't tubing sized by the OD (outer dimension)? 2x2x1/4 or 2x2x3/8 or 2x2x1/8 are all 2x2 on the outside....Or am i missing something here?
\I learned that the receiver (female) part is METRIC tubing.
Local steel supplier carries it.
Also it has no weld seem on inside.
That is just backward, pipe OD doesn't change with thickness- schedule 40 pipe is same OD as schedule 160- the inside hole just gets smaller and smaller. Piping OD is not true sizing as example 2" pipe is 2 3/8" OD regardless of thickness.Correct tube is OD dimensions. Pipe is the ID dimensions.