P5

Create a poly cube

Stretch it out lengthways

Use the insert edge loop tool to divide the cuboid in three

Duplicate it 3 times

Create a square shape with the 4 total cuboids

Select the centre section on the two side cuboids
Move those sections out further

Select the centre section on the top and bottom cuboids
Move that section closer to the middle using the scale tool

Create another cube
Move it into the corner of the frame shape

Use the multi-cut tool to turn the cube into a triangular prism forming a corner at the edges of the frame shape

Duplicate the triangular prism and move one to each corner (rotating them until they fit - you can hold the “J” key to make it easier to be accurate)

Combine these cuboids with the frame using the combine tool

Duplicate this frame shape 5 times

Move the frame shapes up so that they create a staircase like motion

Select the edge of the frame shape furthest to one side
Extrude the edge and extend it so that it reaches the frame shape on the other side
Move the extended edge down until it covers every single frame shape

Create a cylinder and extend and shrink it into the shape of a long pipe
Line up the pipe to the length of the corridor
Select the end of the pipe and adjust it to meet the angle of the corridor
Duplicate the pipes so that they cover the raised centre section of the corridor

Combine these shapes and duplicate it three times
Rotate and move each corridor until you have a crossroads-like shape
In my model, I had two of the corridors pointed upwards and two pointed down, but you can arrange them however you want (I also did the pipe steps and the duplication steps backwards, but that made it more difficult for myself, so I would recommend doing it in this order)

Create another cube, extend it length and widthwise, and use it as the centre for these four corridors
Extend the ends of each row of pipes so that they run into this centerpiece

Create 5 shapes: two cubes, a cylinder, a torus, and a pyramid
Move each of them to the ends of each of the corridor exits (except the second cube, which you want to move to the centre

Increase the size of each shape, around the size you would expect a room on a spaceship to be, and move them so that the edge of the corridors disappears into each shape

Use the insert edge loop tool to “cut out” the space around the corridor entrances from each room, and delete that part

For the cylinder, just delete the face covering the entrance

Take the cube in the centre, and using the scale tool extend it upwards

Inside the other cube that makes up one of the rooms, add another cube and extend it to create a floor that lines up with the pipes in the corridor itself

Moving on to the torus, select a ring of faces on the inner side and reduce their transparency (by holding down the right click button, selecting assign new material, and changing the transparency value from there)

Create 9 spheres and another torus, and move them into the centre of this torus
These will be your planets. Adjust their size and combine the torus with one of the spheres after changing its proportions appropriately

Select the sphere at the centre (which should be your sun) and create a keyframe at the beginning of your timeline
Move further up the timeline and rotate the sun before creating another keyframe
Using the CV curve tool, create a circular path for each of the planets, and attach each sphere to it

Moving on to the pyramid, select the front face and delete it
Select two of the edges of the face you just removed, and extrude them before extending them inwards

Extrude and extend the ends of the pipes to near the end of the pyramid’s floor

Create another cube, and use it to create a long rectangular platform at the end of the pyramid
Extrude, place keyframes and move around the bottom face of the pyramid, similar to how water would move 

Moving on to the cylinder, duplicate it, then shrink the duplicate, and delete everything except the face that matches the back of the original cylinder
Go into vertices mode, and select the vertex at the centre of this shape, then pull it forward to create a cone like shape
Use the insert edge loop tool to create a ring around the cone, then bring it closer to the centre of the cone, creating an indent
Create another edge loop, then bring the vertice at the end of the cone inwards
Select the edge of the area at the end, and select fill hole
Select this new face, and reduce the transparency

Create a sphere, flatten it, and extend it lengthwise
Duplicate it 3 times, and place these 4 propellers around the core
Combine all 4 propellers into one object, then use keyframes and the rotate tool to make these propellers spin

Create a cube, and move it to the centre of this core room, behind the transparent window
Add keyframes so that the cube spins and lifts and droops inside its case

Create two more rectangles, one horizontal, one vertical
Rotate the horizontal rectangle so that it is at around 45 degrees
Use the multi-cut tool to cut diagonally across the vertical rectangle, then select the vertice at the centre and push it inwards
Use the insert edge loop tool to create an indented space in the centre of the horizontal rectangle
Again, select the end of the pipes and bring them into the room

For each of the corridor doors, use the insert edge loop tool to divide the outer frame into three sections
Create a keyframe (this will keep the doors open at the start)
Move further down the timeline, select the inner edge of the doors, then extrude them and move them together, before creating another keyframe

Create another cube, and expand it to cover the entire model, then reduce it’s transparency. I used a water texture for mine, and I repeated that textured around the model, to create a motif of sorts, but you can make it whatever you want. Since there are various gaps in the model though, I would recommend texturing it in a way that make it look safe despite that.