The primary idea for this concept is that you can build a base, a space station, or a vehicle that is lighter and that is also more realistic.
Note: This concept may not make sense as we do not have astronauts yet.
I. Structure
The structure of it is the same as the fuel tank. It can be resized, modified and painted like fuel tanks.
II. Configurations
I propose 3 configurations of this part. Some parts can be changed individually or automatically.
a. Laboratory
the laboratory is where the astronauts will work and do science.
b. Sleeping compartments
Where the astronauts live when they're not working. Multiple compartments can be put depending on
the diameter and length of the part. Each compartments can have at least one (1) astronaut.
c. Logistics
It is where things are stored. Mostly for aesthetics.
III. Windows
Windows on each module can be configured to be on one or two sides. The number and size of windows can be configured.
IV. Mass
It will be lighter than a full fuel tank, obviously.
I second this idea!