I have 2 .223,'s a 300 blackout and a Ak47, now I would like to build a .223 bullpup.  The question is where do I start?  Is there any videos or any guidance anyone might have.  Things to look for and things to avoid?  Thanks

Unless you have a mill, you can't "build" an AR bullpup.  There are bullpup stocks that can accept various actions, but none of them are made to convert an AR.

Get an fs2000, tavor, or Aug. You most likely couldnt build something of the same quality with any of the stock kits out there.

I love my AUG. I'd take a tavor, and honestly, will probably end up with one.

the cheapest way into a 223/556 bullpup will be a bushmaster m17s.

Most builds are drop a rifle into a bullpup stock

ie mini 14 in muzzlelite stock

Only bullpup kit you build that I know of is the l85 kit. Do not know
If the supplier ever made them though

I too suggest buying a already made bullpup.

No bullpup is perfect.  So you decide. The ps90 is my fave but the aug. usr. Msar. Tavor
Ksg rfb fs2000 are also ok but have one thing about them that I do not like.

Tavor trigger is too heavy
Fs2000 trigger is heavy
Aug trigger mushy
Msar has a pretty good trigger
Rfb excellent trigger but ammo sensitive
Ksg not reliable until broken in. Jams are nightmares.