I recently wrote an X-ray shader which renders hidden parts of  an objects because I thought it might be useful in many upcoming projects! But when I wanted to integrate it into a game, I realised that I would have to write a new shader whenever I would want to combine the X-ray with another shader(diffuse, toon, or other shaders).

Partly because of laziness(/not wanting to do the same small task over and over again) and partly because I always wanted to create an unity editor extension, I started to create one which would automatically generate a combined version of multiple shaders.