I am building out some code using Eclipse's JDT tools - I'm using JDT Core component. However, It seems that I can only build out code using the JDT Core component within a plugin. I was hoping to maybe access some of the classes from the JDT Core component from a regular java project. Is this possible?
All the JDT components/plug-ins depends on the Eclipse framework and therefore - by extension - will any code you write depend on the Eclipse framework and runtime. Thus, your code must be in the form of a plug-in.
Converting a regular Java project into a Eclipse plug-in is rather simple. You just need META-INF/MANIFEST.MF (or an extension of the one you have) and possibly plugin.xml.
But... why do you want a regular Java project in the first place rather than a plug-in? What differences do you expect - apart from the mentioned files?