This app can open/load/view wavefront(.obj/.mtl) files. You can use the file sharing ability of this app to upload your .obj files to your phone.

This app can also load textures, but it can only load .tga files.

Use one finger to rotate the loaded 3d model. Use two fingers to scale and move. And slide your finger at the bottom of the screen to rotate alone the Z axis.

Wavefront(.obj/.mtl) file is a type of file that holds a 3d model. The 3d model can not be modified through this app, it can only be viewed. You can use 3d modeling soft wares on a computer(such as Blender) to create this .obj file.