Design-time support requires additional effort, and if you need some of the more advanced capabilities, this effort is not trivial, but it's generally also not too overwhelming, so if you're up for it, here's the documentation you need to consult.

For simpler tasks, it can be no more complicated than adding some attributes to properties which make them visible in the Properties window in the IDE. But tasks like providing custom editors involve creating your own editor classes - by deriving from the existing ones, or from scratch.