Hey guys i am trying to get my gun model from blender into unity but when i export as a .blend file and put the file into unity some of the models faces dont show?
How do i export with double sided faces? Or any other ways to fix this?
Please help. Ty.
It could be that all of the faces are just inverted in Unity. Try fliping them all in blender.
You need to flip all of the “invisible” faces.
You can check this in blender by changing the texture mode.
Look at your model in blender:
Looks ok, right? This is with the display in “solid” mode.
Change the way the object is displayed to “texture” and you see this:
Select those faces:
Hit the “w” key to get the specials menu and choose “Flip Normals”:
In “texture” display mode, it will now look like this:
Problem Solved!
A few other things:
You can get to “Flip Normals” by choosing “Mesh/Faces/Flip Normals”
You can also try using the button “Normals: Flip Direction” from the side bar:
For more complicated geometry where you don’t want to do one face at a time, you can try using the button “Normals: Recalculate” (see image above) and then use the options window at the bottom of the side bar to select/deselect “Inside”:
Moving to 3rd external tools…
I think the objects normals needs to be fliped the wrong way in blender, in order to look correct in Unity. I have a character that I put into Unity and all of its normals were fliped. So I had to change the normals in blender and reimport it. Now it looks correct.
Odd! I’ve never seen that, actually. Could be a unique case.
I find that if the normals are correct in Blender (checking via “Textured” mode) they are correct in Unity.
If you have problem to get your normals nice and clean, check if you don’t have non-manifold faces. It can prevent the “recalculate normal” tool from working.
I never had inversion of normal between unity and blender either.
Ty so much 
solved that problem