Math Teachers' Pencil Holder / Stand, Hyperboloid, Ruled Surface

#####Math Teachers' Pencil/Straw Holder /Stand, Hyperboloid, Ruled Surface

This is a classic display for a ruled surface (hyperboloid) using classroom pencils or straws (see David Hilbert's famous book on imagination and geometry). It comes in four versions: two hole diameters (8.5mm and 9.5mm), single or dual rings). The outer diameter is 127mm or 129mm, respectively. It holds up to 48 pencils or straws. Once some pencils are inserted, try to lift the ring up slowly and allow the pencils to drop a bit for a symmetric structure.

Have fun and do not get mad when things fail to work as expected.