The moment I found out about the LEGO Ideas Ball labyrinth, I had to have it. I'd always been fascinated by the classic wooden ones.
"I'm going to buy it," I declared, "even if it costs $60!"
If you've seen the set, you know it costs $70. So I built my own.
Building the Beast-
This thing is massive. LEGO's would look small next to it. I needed to be able to build the maps on 32X32 base-plates, since I don't have enough plates to construct a smaller size.
The scale presented an unexpected issue, however. Mere techinc axles couldn't control the tilt; they would twist against the weight. Eventually, I thought of using 2X2 round bricks instead, and the problem was solved.
Moon Base. After a Bricklink order of 2X2 tiles, I was in business.