This so far includes engines, fuel tanks, fuel generation, clearly stated debug items, all high-temperature parts (very expensive), air compression for spaceflight, and DarkEnergy engine boosting (DarkTech engines only).
More useful parts in this cost multiple fortunes so refueling a ship on your way to an outer planet is cheaper still, but if you have plenty of moneys, this is a worthwhile investment in your space program.
The fuel generation is extremely slow and consumes multitudes of charges of DarkEnergy capacitors to fill a medium-large tank.
The debug parts have no physics (that's mass, drag, and lift) so they will not affect your craft's performance in any way, just its looks.
Here is something that I am working on. This is the DT-808 model, but the textures are messed up :/
https://sketchfab.com/models/cf4bbe95eada414daf10bf145e4eb085