1 Get a prop for a wall then stack it (Best walls are Blastadoors and PHX tiles)
2 Make sure your wall prop is on a corner so that it is straight.
3 put your wall prop against a wall then stack it to how long you want.
4 Now put another wall prop on the other side of the corner.
5 do step 3 for that wall
6 now adv dupe one wall
7 put it so its alligned with the opposite side of the wall
8 do steps 6-7 for the other wall
9 now wield all walls
10 stack the walls so it goes up
11 now have a cieling prop
12 wield it
13 use fading door tool or doors tool for the door
(optional)
14 decorate it
15 have a floor
16 make stairs
17 have another floor
There you go you have a base now.