Bill Cutlers Mega Six Burr, Modifiable

Yet another extended puzzle from Bill Cutler. This is definitive one of the hardest puzzle, ten steps needed to remove the first one!

Please keep in mind that Bill spend a lot work on it and thankfully did not patented it. Nevertheless you might want to sponsor him by buying a nice wood version of this:

http://billcutlerpuzzles.com/stock/megasix.html

This STL models have 0,4mm tolerance, so it works also fine with filament which extends a lot, but it is a bit loose on the other side.