If you want to build a ship with those same big rooms you can get those at the manufacturers HQ. Biggest once are 3x3. Cool stuff indeed!
Nova Galactic: ship service technician at New Homestead on Titan in Sol. Deimos: Deimos Staryard above Deimos (Moon of Mars) HopeTech: shop at Hopetown on Polvo in Valo Stround-Eklund: Stroud-Eklund Staryard above Dalvik in Narion Taiyo: shop is at Neon on Volii Alpha in Volii (Elevator in Ryujin Building)