3/8" Threaded Rod Holder Base, " In a pinch" for under $1.50

[blackfish]

Where did u buy?

["G"]

You can get them at Lowes or Home Depot...its a 3/8 ceiling fllange that is used to hang pipe.

[skeetbum]

Push came to shove you could weld that to a bigger square of steel and powder paint for the bigger mount. Great find, That's smart thinkin.

[okhawg]

They are harder to find, but you can find those fittings in 1/2" also.

[Slabyanker]

I made my own at work one day. 16 of them. 3/8" x1" flat bar stock cut 2" long. Drilled 3 5/16 holes. Tapped the middle hole 3/8-16.