I have a puzzle made by Eric Fuller and designed by Yavuz Demirhan. It is the Rail Box. Quoting Eric Fuller this puzzle looks just like another caged burr at first glance. It's only after playing with it that the genius of the design is apparent. Four identical pieces dance around two longer horizontal pieces to create a unique level 18 solution. Not only do you need to determine the position but orientation becomes important as well. A nice challenge for the seasoned puzzler yet approachaable for the intermediate/beginner.
Fit is extremely good on this puzzle with a nice slide at average 50-60 per cent humidity. Cage is shouldered for strength.