OctaBall #1 Puzzle

Four (identical) pieces assemble into an “OctaBall”, my name for an Octahedron intersected with a sphere. Assembly is surprisingly difficult. The pieces have no symmetry and appear warped or tilted (your printer is not messing up).  It is remarkable that they can assemble into a symmetrical shape. More Octaballs with different pieces are in the works.

WARNING: Assembly is challenging, you may even conclude that it is impossible! It is impossible if you add one piece at a time, but how else can you accomplish it? If you are really stumped, this video should help (not exactly the same puzzle but very similar)

Taking them apart can also be tricky, there are at least two ways to do it. One technique requires careful observation and good grip strength. OctaBalls are more difficult when all the pieces are the same color; I recommend using at least two colors.

Print four copies of the basic piece “B1”. I found an orientation where the parts print cleanly without supports. But it doesn't contact the bed as well, so I include a 2 mm brim.  The pieces have an offset of 0.07 mm.

WARNING: These models are a good test of your printer's accuracy.  If the pieces are not printed accurately the puzzle will not fit together.  Do not rescale the pieces smaller, they will no longer fit.

Variations: Piece B2 is included as an optional variation.  If you print 4 copies of B2, they also assemble into an OctaBall.  In addition, 2 copies of B1 and 2 copies of B2 will also make an OctaBall.