[Tex-Twil]

I think unless you plan to release this publicly then there is no problem with using his images and guages, if you do plan on releasing something public then if he does not answer and you do not find anywhere where has said that you cannot use the guages for your own projects, and if he doesn't answer your emails or whatever then once again it fine as long as you credit him properly.

The application will be definitely public. I'm not sure yet I will sell it or make it free.