A frac-3-tile shaped like a rectangular hourglass, which intersects the side of its bounding box in canonical central thirds Cantor sets.

(c10)
hourg(2,.001)$

(c9)
Block([plot_style:dragstyle],hourg(10,.001))$

Note that half of this figure is also a (rather nondescript) frac-3-tile. A 30 minute glass?

(These pages are from Macsyma notebooks exported as htms automatically.)