This is how I made mine.
Using a piece of 2" tube.
I slotted it down 4 sides, about 4".
Then I spread it apart till it fitted the 4 pipes.
I then cut out 4 wedge shapes to fill the gap.
Then just fettled and welded it into place.
As Ash says though, don't forget to weld between the 4 pipes
before you fit them
