Bunning has this ( 14 mm ID tube ) cut 6 pieces 50mm long and zip tie them together which will hold shape while you tack weld one end = 50mm OD
This is then welded to 76mm x 50mm concentric reducer - baffle is then welded to 14mm sections
which is then trimmed so it fits inside 50mm end blank ( supported )
I have done it this way so as it can be repacked at any time , and internal baffle is supported at opposite end
( Pause refill )