- Edited
Many modern multiplayer ships use internal engines to increase maneuverability and speed while keeping the engines greatly protected, but the downside is that the thruster’s exclusion zone prevents any components or paint jobs from being applied there. It’s fine for multiplayer, but quite a few faction and aesthetic ships greatly struggle with this artistic constraint. Blocking additional components on exclusion zones is perfect, but I have an idea how to place paint over the exclusion zone without breaking multiplayer balance - an optional sheath for the engine exclusion zone.
Currently, engine dead zones are completely visible, but what if, for each tile, an optional 1x1 “sheath tile” could be enabled to cover that tile of the exclusion zone? These sheath tiles could only be enabled if that tile is adjacent to at least one non-exclusion zone tile or non-empty tile (like armor, corridors, any tile that takes up physical space). Another spaceship building game, Kerbal Space Program, uses this exact method to great effect, with it’s optional sheath that can cover an engine, making it incredibly less unsightly: 
The engine sheath:
The UI KSP uses to toggle the sheath (part of the UI is from a mod; the UI for the sheath is on the right):
For balance, the sheath tiles could have 1 health and disintegrate upon any damage (and allow the projectile to pass through, as structure does), so that sheath blocks don’t become essentially free armor.
And the best part: If a player doesn't want to use sheath blocks for their engines, they can just leave the exclusion zones exposed, so existing meta styles aren't forced to change!
With sheath blocks, meta-based power is preserved, balance is unchanged and players have more freedom to customize their ship artistically - a major pro for a building game like Cosmoteer!