A space filling solid where the planes show a Haeckelite-like arrangement of pentagons and heptagons. twitter 
What was widely referred to as 'the' scutoid in most articles has a pentagonal face on one side and hexagonal on the other, and that *isn't* a space filling solid.
This has a pentagonal side and a heptagonal side, arranged as in pentaheptite. wikipedia wikipedia
Designer Dan Piker posted the design at a site that wanted a login to download. I asked for a more local post and was given one. sketchfab github
//scad.fed.wiki/assets/viewstl/viewstl.html?stl=http://scad.fed.wiki/assets/pages/haeckescutoid/hollow-toid.stl HEIGHT 370
pages/haeckescutoid
module hollow() { hull() { translate([0,0,-1]) scale([1.3,1,1]) cylinder(1,d=14); translate([0,-1.6,21]) scale([1,1.4,1]) cylinder(1,d=8); } } difference() { import("haeckescutoid.stl"); translate([0,8,0]) hollow(); }
We revised dimensions several time until we could see that the sides were sufficiently thick to print. Here we were close but not thick enough yet. This slice at about 110 out of 200 layers.
We see regularity in the assembly animation included in the twitter posts. Notice how pairs fit together.
