Why does the meshpart I imported from blender look like this

[ProtoBugg]

I’m pretty sure I followed the tutorial correctly, so why is it hollow like this?

[Cyafu]

Your normals aren’t correct. Make sure that the normals on the faces are facing outwards. In edit mode, select all the faces by changing to face select mode, pressing A and then pressing Alt + N and then hitting flip.

[samuelsg]

This is why (here’s a video which will explain everything about this) : https://www.youtube.com/watch?v=IMkS4ZR_TRc