So this next bit is going to be a list of things BD doesn't do or offer, maybe they did once, or not at all. That and I get confused after a while and need to check via ticket again.
Things BD will Not Do
Ika cannot support Highlights
Pearce cannot support Highlights (or fades)
Gunner, Fenrir, Scorn, and Rex cannot have highlights (was told the knots cause issues and Scorn has a heavy curve)
Penetrable colors cannot be swapped onto Insertables and vice versa (past issues/manufacturing limitations)
Glowing Toys cannot have a Glowing Highlight as well (Unless it's a promo or premade color. So Jesters Queen or Telepath cannot have GITD highlight vs. Sky Spirit which has one).
You cannot have a highlighted toy besides White or GITD (of one of the 4 colors) and it cannot have glitter in it.
Can only have one of the above highlights not both.
Pretzel, Nocturne, Zaratan, Sleipnir, Scorn cannot have fades.
Aurora cannot be requested
You cannot request unpigmented silicone as a color choice.
Stan, Rex, Hunter, Razor, Xerxes, Kage, most toys with balls besides Echo and Bruiser, and Meng cannot have a Split Base.
Nocturne and Zaratan cannot have marbled shafts (something something the curve causes colors to smear) though Nocturne used to be able to support a pridestreak (think B & W cookie) if ticketed. Unsure if still possible.
Most fades that require a ticket seem to have disclaimers. (Just an observation)
No marbles can have more than 3 colors
Bases usually only can have 2 colors*
(*have been told if the base is large enough it can have 3 colors. Last year. Elise)
Rex's Good boy/Signature cannot he replicated on other models.
Old Signatures (Absolute Zero, Tyrannosaurus Sex, etc) cost the same as if custom (Absolute Zero was a split fade, so 30$ for example).
You cannot request a marble of two existing glow colors (no Tyrant blue marbled with Sky Spirit's purple for example, but you can't modify the colors these came on (aside from if it's two colors a pridestreak COULD be a thing. Info unclear if we still can. You can order these as a solid base or shaft color however.
Cannot add glow pigment to other colors.
You cannot request stripes (like red velvet cake) in different colors
Same with pumpkin pie, colors can't be altered.
Any changes to the options on the site (Nova's Natural but with glitter or metallic) will change the toy to a custom and will cost more. (Nova's Natural; base 10$ + fade 20$ + glitter/metallic pigment 0$ (free) = 30$)
You cannot request how the pridestreak splits the two colors, how loose or tight a marble is, or location of colors (all peach shaft but pink head for example)
"Surprise Me's" can have only loose requests (no flesh colors, no yellow, etc). If you request a surprise me with a picture attached they will ask if you want a fade or marble and will charge as such (I tried attaching a pic to see the resultant response. Never ordered it)
If anyone has any additions @ me
Also please don't blame CS for the "manufacturing limitations" CS just follows what the higher ups tell them.