My first pep mando pistol (clone wars)

[Jokerjack350]

Hey everyone, I'm new to this whole 3d modeling thing and i just finished my first model of a mando pistol from clone wars BUUUUUUUT i imported into Pepakura Designer 3 and i get grey faces and red line on part of the gun . I have no idea what to do so if anyone could help i would it would be greatly appreciated.

-Jack

p.s I used blender to model it.