Weld on fittings for tube - what are they called, where to buy?

[RIP]

I’m trying to fit various parts like passenger assistance handles, to the tubular frame on my buggy. The problem is the handles have a flat surface, which doesn’t sit well on a 2" tube.

I’ve searched online to find some sort of weld on fitting. I haven’t found anything suitable, except for one image without any product details. Do I need to get these custom-made, or does anyone know if this kind of part is commercially available?

 

[carbon]

A quick search has shown these, I expect other companies produce them as well

Weld on Bosses

 

[Mikey D]

2" Wrought iron fittings ? BSS or similar merchants ?

 

[Prajna]

Or do some notching.