Well, I'd start with assuming the majority of visitors will expect a framework, and countering that with explicitly saying THIS IS NOT A FRAMEWORK! very early on on the website. Expectation management will go a long way.
Maybe a search box with "what topic would you like to play around with?", with some optional checkboxes to refine the search query (for example, maybe I want to work in the browser and limit my results to TypeScript and ClojureScript. That would also help a bit with getting the "toolbox" aspect across.
Another idea is to have example projects made with thing (the portfolio part) that also clearly demonstrate which of the libraries were used.
Maybe a search box with "what topic would you like to play around with?", with some optional checkboxes to refine the search query (for example, maybe I want to work in the browser and limit my results to TypeScript and ClojureScript. That would also help a bit with getting the "toolbox" aspect across.
Another idea is to have example projects made with thing (the portfolio part) that also clearly demonstrate which of the libraries were used.