PolyBot Socket Ball Holder (Q45882)

I reached into the way back machine to modify this design. While my wife was putting together her PolyBot, she cut her finger on the sharp corners of this thing: http://www.thingiverse.com/thing:5126 As much as I love that design, it was innevitable that sharp corners would cut someone. My wife's comment was; "If you're going to have kids assemble this, there can't be any sharp corners". This thing takes a different direction than the socket based joint. Instead of using 'sockets', it uses protrusions that can grab onto the dimples of another thing. In this particular case, it will match well with this other thing: http://www.thingiverse.com/thing:8272 Combined, they form a vertex/joint that can bring together three rods of any size. A nifty thing for building space frames. You can change parameters in the OpenScad to adjust the size of the protrusions, or the width of the slot, or whatever.