Discovered (with a computer) and made by Bill Cutler 1989, level 5, 7 holes.
(Maple, 3.5 inches)

A programmer's nightmare because disassembly requires a twist. Move F up 1/2 unit, rotate A 90 degrees, move A up (pulling F with it by 1/2 unit), move D up, slide D out. Note that although the 1/2 move is needed theoretically, there is enough play in the puzzle that F can initially be moved up a full unit (this does not change the level since A has to be moved up in any case). This puzzle is hard for a person too, because according to Cutler's computer analysis, there are 102 assemblies (ways these pieces can exist in space in the solved shape) with only this one solution (the only way that is achievable starting with the pieces apart).