Augmented Four Corners
Designed, made, and sold by Stewart Coffin in 1970's and early 1980's.
(Cherry and Rosewood, 6 pieces, 4.5 inches;
one of 6 puzzles purchased during a visit with the designer in the early 1980's)
Described in Stewart Coffin's book
The Puzzling World of Polyhedral Dissections;
here is some of what he says in the directions that came with the puzzle:
"The Augmented Four Corners Puzzle consists of six dissimilar interlocking pieces which assemble in one way only,
with one sliding axis,
to form a geometrical solid with tetrahedral symmetry."
Use the three pieces shown below to put together the top
(shown with a rubber band)
so that the "legs" that hang down have vertical sides that will slide down onto the other three pieces.