How can I create a chicken substitute? How can I create a homemade product with that has the texture, flavor, and cooking properties of chicken, but is vegetarian (or vegan)?

I'm inspired by the Lightlife, the Sipz orange "chicken", and Veggie Grill "burgers" but am looking for something more flexible that I can make myself. 

I'm not looking for a specific recipe, but rather general techniques and ingredients to use as a starting point.
Seitan (aka. wheat gluten/vital wheat gluten/wheat meat/fu*) can be used to make chik'n nugget type chicken, but not as in breast or thigh, etc. Recipes abound on the internets.


The gist of using it involves bringing together compositional ingredients (basically the gluten) and flavoring, mixing to develop it into a rubbery mass, forming it into and using as a dough (i.e. making chik'n nugget cutouts).


*There are differences between these, but they are all basically the same beast.