Thanks for your answer.
What I probably forgot to mention is that I already have the shape as a mesh and want to rebuild as a solid; I could just transform what I have to a solid (I know the way you've shown). The issue here is that the many polygons make working with it a real pain and can throw off the Path tools (although they've gotten far better at dealing with this kind of stuff even in the last few weeks).
That's why I want to rebuild this shape as a solid in the first place; so I can work with it as a solid.