Alright, so I *finally* got all my ducks in a row on getting a plugin to work both in the Qt Designer and not give any linker errors on compilation etc..

My main issue was that I get receiving linker errors when I had built it as a DLL; the only way to solve those errors was to include the .h and .cpp files directly in with the project, but that's defeating the purpose of encapsulationl! So I went ahead and finally attempted to build the plugin as a *static* library. This replaced the old .lib file and it all works now! (It's worth noting that this was more than one class. The plugin class used another custom class. The dynamic library presumably wouldn't compile my other custom class in with the plugin class and gave me linker errors.)

I guess my question is:
-Why didn't the DLL compilation compile both classes into it's .lib file but the standard library compilation did?

I investigated the issue pretty thoroughly but I have not figured it out yet. It's worth noting that I have not built .lib type files in the past. Help understanding why this fixed my issue would be much appreciated.
Thanks!