I am considering building a custom DI container, as it occurred to me our own custom providers or even the out-of-the box providers do most of the work. I had been describing the 'provider' to other coders as a powerful factory for a long time. Looking into Ninject, I found they describe how their DI bindings are resolved by a provider:

snip

Okay, so remember when we said type bindings were from a service type to an implementation type? Well, we lied. You caught us. Type binding is really a little bit more complicated than we let on. Rather than being from one type to another, bindings are actually from a service type to a provider. Simply put, a provider is an object that can create instances of another type. It's like a factory, but specifically designed to work with Ninject.

/snip

Ninject is referring to their own concept of provider, but replace that with an ASP.NET provider or any one that pulls in XML config and you have the beginnings of a tiny DI framework.