User imports own .obj file?

Hi - I’m new to Unity3d but I’ve come for a specific purpose. How would I go about using it to create an app where the user imports their own .obj file and thus be able to view a 3D model of it, rotate it etc.?

Just load the obj file normally, as any file (they are just plaintext files, try opening them in notepad). Then create new object and set it’s shape to obj shape. Also look at Unity - Manual: Model file formats