Remains

Create a 2x2 base.

To start building your base, you'll need to craft the Blueprint item (5 Plastic and 3 Wires) that's found on the first tab in the Craft menu. Once crafted, select the Blueprint and by default it selects the Base (Floor) option. You can change the build pieces by holding down LT button and pressing RB and LB to change the pages. For this just place 3 floors, 4 ceilings (including over the computer), 7 walls, and a door. Can be done in creative.

For those wanting a more legit experience:

Base (Floor) - 10 Scrap Metal and 2 Metal
Wall - 15 Scrap Metal, 3 Plastic and 7 Rubber
Door - 30 Scrap Metal, 15 Bolts (unlock recipe) and 10 Rubber
Roof - 10 Scrap Metal and 3 Plastic