Box has no inside

I have managed to get a blue box in game, but it has no inside.
I extruded and scaled the other end of the box and extruded another box that fits inside the original box.
Now the parts that i extruded are invisible.

Its also weird that the back of the inner box is black.


Thanks for your attention

 

Check if the faces are inverted

 

Did that, but in game it looks the same. I used "flip direction" and then re assigned material, re made smart UV project, then exported .dae and overwrote old files in vehicle folder. Is this the right way?
Also this doesn't look like correct to me. I don't think those areas are meant to be black... these happen to be the same areas that are invisible!

 

To flip normals, you just need to select desired faces and hit Ctrl+N

 

Flipped the faces using ctrl-N and did everything again but they are still invisible :/
Also, the inside areas in the UV map still look dark. They're not black anymore, but have a black-blue gradient so still darker than other areas.

 

Ugh... Does the mesh have only one "side"? That would usually cause that. Best to use Solidify for that

 

Thanks, i solidified (idk so much about that but i applied that) and tried ingame but it's still invisible from inside. I think I should start again with a simple model without inside, just the outer surface and look if i get that to work
The main thing in this was that i finally understood materials and how to get the model show ingame without the "NO MATERIAL" texture, so i wanted to make the model perfect in case there was a quick fix to that.
But it didn't work so i'll do a simple model.
Also, i'd like to know how to make proper "thick" parts that high quality models have, as i haven't got that kind of model show complete ingame yet. (If its the Solidify tool, just tell me more about it!)

Thanks to all who replied!

 

Well, mainly Solidify is used for that... OR you could go the super hard route & duplicate the outside, scale it down & then align stuff like it should be. Usually Solidify is the way to go for doing such stuff, but it happens that it leaves behind some unnecessary "residue" like pinched egdes where there was a lip on the mesh. The settings in it aren't that hard to understand; the name of them is what they do

 

Thanks! I was looking for this kind of info