I’ve always been interested in writing VSTs, but haven’t really known where to start (I also need a motivating idea for one, but I’m sure that would come.) Do you have any resources that you would recommend for an experienced programmer and composer?
VST 2 was not so hard as you would imagine to get started. They are just a dll with a well defined interface. Sadly 2 is now deprecated by Steinberg but probably available. Don't know about VST 3.
However ... getting deep into DSP is another thing!