Once you find the right combination of 'workable' surface notches, the keys will then separate .
The orange Dool-'o'-rinth . . . . . 'simple'
There are six colors of progressive difficulty levels :
easy yellow . . . . . simple orange . . . . . silly green . . . . . complex blue . . . . . crazy red . . . . . terrible black .
To quote a fellow collector friend of mine : "..... maybe they rate by # of dead-ends? Distinct passages? Total solutions (fewer = harder)? Length of solution passage, or number of turns or
sleeve . . . . . the maze .
top of shaft
This part is stamped 'CorToys' .
bottom of shaft