Table Pole

Go Bunnings and buy some gal pipe. 20 or 25mm. Comes in various lengths with threads on the end. Then just buy a suitable "T" piece gal pipe fitting as well. Couple of saddles to suit and you,ll have your leg.

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Maybe one of these?

I think the OP wants an extendable fitting ( pipe within pipe) , if I'm getting the general gist right.

Maybe something like an extendable tent pole from a camping store ?

Cheers
Jim

Maybe this one - Table-leg Bi-Fold, Max 675mm.

Alternately, is there a men's shed within a reasonable distance. A lot of them do metal work. They could whip one up for you.

That is a neater set up but when I done mine I bought a cheap gate hinge from bunnings screwed it to the table and screwed on an adjustable tent pole with a plastic bracet to clip it to when not in use works a treat.

Yes, I am after an extendable one and perhaps the idea of a hinge attached to a tent pole is the way to go. Tanks for your input everyone.