Can I pin and weld my own barrel or do I have to go to a licensed dealer or something?

Of course you can!  The finished product is what matters, not who did the work!

get a pack of like 20 bits of the correct size.
use one to drill the pocket in the barrel.
snip the shank off just short enough to sit below the level on the brake you're pinning.
weld the hole over.

depending on how crafty you are, at least 2 brakes per bit that way.

The question of "can you" is a question only you can answer as it addresses your skills. The question I imagine your asking is, is it legal to do it yourself. The short answer to this is, yes. But when you look into the logistics of doing so, if you possess all the components to put the firearm together before doing the pin and weld on the threaded barrel, possessing the threaded barrel violates NJ law

On 11/1/2020 at 11:25 AM, fslater said:

The question of "can you" is a question only you can answer as it addresses your skills. The question I imagine your asking is, is it legal to do it yourself. The short answer to this is, yes. But when you look into the logistics of doing so, if you possess all the components to put the firearm together before doing the pin and weld on the threaded barrel, possessing the threaded barrel violates NJ law

Please...no more of this stufff...my nerves cannot take it!,,

It's only a crime if you get caught. 

Don't have all the parts in your car and drive drunk, speeding, with two burned out brakes lights and a busted headlight and you'll be ok.

at least cover it with a dead hooker and a couple bricks of coke.  you can say you're handling some business for Hunter Biden.