For what it is worth, here is a little 'history of the custom' head for each character that includes images (sorry, tried to get all images in to one file but it just looked sloppy. If anyone else wants to take a stab at consolidating it into one 'easy to quote' reference, please feel free).
HUDSON
-EVA Models (Chris "FNG" Chulamanis)
1st one ever, pre-dating Hot Toys I believe.
-"Hero Heads" (Lonnie Hale/H2Creative)
Image from SpaceJockey
-"Chronotoys"
Paintwork from image done by 'Figuremaster les'
-Joy and Tom Studios / "Snyder-man"
All 3 variants still available! Can be purchased painted or unpainted
-"PoppoToys" (Bill Kern)
(forgive crap paintwork image! That one is mine, still have some practicing to do...)
HICKS
-Hot Toys "Stoner" head (Vietnam Navy SEAL figure)
Story goes they sculpted it, then "hid" it on another figure when they failed to acquire the actor's likeness rights. They also "hid it" on their "Hudson figure" with paint so bad it was unrecognizable.
-"Figuremaster Les" & "XenoViper"'s take on "Stoner" (resculpted "Spikey Hair")
(Imagine & paint work from SpaceJockey)
-"Hero Heads" (Lonnie Hale/H2Creative)
(would love to add image of 'painted version' if anyone has one)
-Joy and Tom Studios / "Snyder-man"
Still available! Can be purchased painted or unpainted.
-"Sculptor" (Rocco)
In pre-preduction. Available soon.
APONE
-Hot Toys default Head (repainted)
(Image from "V-Raptor", Paint by "Maximus Studios")
-"Hero Heads" (Lonnie Hale/H2Creative)
-Joy and Tom Studios / "Snyder-man"
Still available! Can be purchased painted or unpainted
-Kaustic Plastic KP03
Debatable if the likeness was even intended, but I found it close enough to be worthy of mentioning