Anyway, looking for some engineering inspiration I found a nice page with all the all-time problems addressed.
http://makezine.com/2012/04/13/cnc-panel-joinery-notebook/
It's just another variation of the "puzzle" solution with a tiny center hole, though.
http://makezine.com/2017/02/06/math-monday-triangle-phun/
Nice, but it requires two type of solids to fill all spaces. It's not like I don't know the answer but still looking for a product.
A new cave has been found.
http://new.huji.ac.il/en/article/33424
I doubt there's much to get out this ruin or weathered place.