My old friend Chaim Clorfene has constructed scale models of the Third Temple (following the Ramchal's understanding), and has published a book with detailed plans and models. Here's a sample page from the book:
He lectures around the world using a PowerPoint presentation. He lives in Tzefat, but is in Chicago now and will be there for several more months, so now is a good time to have him speak in the US and Canada. You can reach him through his website.