How to make a custom object "chrome" or Transparent?!

[Mudbill]

Retexturing each face only relocates the UV maps. It's still the same material. You have two options: Either make all the texture for your turtle into 1 texture file, or keep the different parts separate objects.

As for the model viewer, it might happen to mess up the shape (usually always happens to me). Fix it by deleting the .msh file it generates first and then reload it and it will look like it should (assuming this is the same issue).