binding barrel bolt meets a carriage bolt

[hanermo2]

A peen, aka pin punch on one corner of the flat blue bolt flat area will mostly lock it in place.
This can be done in an inside-supporting fixture, think fork, avoiding distorting the U shaped hold.

Any industrial epoxy will fix the blue bolt, depending on load and the size of the end plate surface area.

A fast small drill through the holding bolt edge (blue), and a pin, punched, would also work.
So would e.g. blind pop rivets.

Press-fit barrels would definitely work.
Both for holding them, and the ends pressed in.
They need precise holes for press-fit purposes.
Think reamed to 0.01 mm in D, more or less.

Typical std reamer accuracy (0.01 mm in smallish D), easy to do, cheap, fast.

Custom barrels are probably much cheaper than anything like that from mcmaster in qty 3000 units.

Typically, mcmaster/misumi/etc cost 1-2-3$ for engineered units of any precision.
Industrial epoxy will likely cost 1$/unit, +/-, in small quantities.
Total 4$, or so, qty 3k total.
Plus lots of work in assy, several $ each. You cannot assemble 60 per hour.

You could get 3000 units of barrels and fitments and an assy jig (pop/rivet/pin) made by any jobshop for around 10k$.
And maybe a drill-jig to make the forks yourself.