This was kind of an unusual request by a geeky friend a thousand miles away from me. He thought this up, designed the maze on an Excel spreadsheet, then used that data to make a drawing of disks with appropriately-placed notches which when glued together creates an cylindrical internal maze. Made a few test cuts and had to make a few design changes to allot for machine/bit limitations (as well as the 1/4" plywood that is never 1/4"). I verified the design worked, then sent the disks to the customer and he took over assembling, sanding and oiling the project.
It's actually fairly tough to open it as you really have no way of knowing where you have and have not been!
There is a cup at the far end of the cylinder, which if all goes well, will house an engagement ring.