This is a list of the PB to camp for QL250+ Control Symbiants, and where the pattern pieces drop. I've excluded some symbs that almost nobody uses (such as right arm and the wrists), if you need to find them, go to http://aopocket.tngk.com/, where much of this information was gathered from.
Ahpta (QL 220)
Drops from: Atakirh & Salahpt (around Razor's Lair)
Engi symbs from this PB: 270 eye, 250/270 brain
Haqa (QL 220)
Drops from: Akshk'i & Tuq'usk (Near Oasis)
Engi symbs from this PB: 270 chest, 250/260 left arm
Sasabonsam (QL 220)
Drops from: Anansi`s Disciple, Scary Spider (some Anansi quest mobs as well) (South-Southeast of 255)
Engi symbs from this PB: 250 thigh, 250/270 feet, 250 left hand
Shullat (QL 255)
Drops from: Tinos, Astypalia, Phatmos (West of Razor's Lair)
Engi symbs from this PB: 280 eye
Taille Frees (QL 220)
Drops from: Aniitap's Shadow, Aniitap, Wicked Shadows (Between Inf Redeemed Temple and Ergo)
Engi symbs from this PB: 260/270 waist
Ushqa (QL 220)
Drops from: Maychwaham, Ushamaham (Near Oasis)
Engi symbs from this PB: 260/270 ear, 250 chest
The Night Heart
Not a PB (Pandemonium)
Engi symbs from this mob: 300 eye, 300 brain, 270/300 ear, 280/300 chest, 270/300 left arm, 260/270/300 waist, 250/300 right hand, 250/270/300 feet, 250/290/300 thigh, 250/280/300 left hand
For many of these, if you're just starting off, the easiest path of camping is to start at the Oasis, kill the Merlin Dragons there, move West past Razor's Lair to the heck spots. By the time you kill Astypalia and Phatmos, the first dragons are bound to have spawned. The easiest way to solo these is to leave pets on wait in a safe area far from the clusters of mobs around the dyna, use the IS DoT ring or hacked blister packs of low level Doctor DoTs and then run back to your pets. If you've left them sufficiently far behind, in a minute only the boss should appear, at which time, send the chicken (trimmed for aggressiveness) and then a bar later, the dog. If you use a top QL aggro trimmer, you should be able to spam Maker's Touch and Rejuvenate without getting aggro, saving Mechanic perks and Regrowth for when your pets get low. Using this technique, I've been able to solo every pattern mob here except Scary/Disciple (Sasabonsam) and TNH. I havent tried soloing the PB themselves, as there's usually a nice org mate or two (or Alcoydel and Gaged <3) to help me. Additionally, it should be noted that almost all of these PB are Inferno Garden mobs for one side or another, so things like the 260/270 waists that drop from Taille Frees are cheaper on one side's GMS than the other. Make friends across the isle and ask them to check if you dont feel like farming your own symbs.