Did you ever want that .NET will look your .NET assemblies on path you can control on. well there is a way to do it by using DEVPATH.
Developers might want to make sure that a shared assembly they are building works correctly with multiple applications. Instead of continually putting the assembly in the global assembly cache during the development cycle, the developer can create a DEVPATH environment variable that points to the build output directory for the assembly.
Read more How to: Locate Assemblies by Using DEVPATH.