How to test on custom images

[ayushgupta9198]

Hi @fogleman

I am following your model code for generating 3d stl file bu however i need to know we can execute the same code for custom image generating mesh just like the butterfly image and its mesh creation that you have shared in sample.

I have also followed the steps for generation but got
`ImportError: attempted relative import with no known parent package

can you help me in custom mesh generation
`