The "keel" can be constructed in Moi, from a Cube:
https://en.wikipedia.org/wiki/File:R1-cube.gif

The "corner" with 3 rhombi is the keel, the unit for the illusion of cubes.

The acute angle between faces seems to be wrong??? It is supposed to be 70.528779 degrees.
Not getting the Maraldi angle, 109 degrees, 28 minutes, 16 seconds ...
(I must have made some mistake?)

- Brian

Some of these papers are very hard to follow...

An old link with keel angles for bee honeycomb, of rhombi.
https://www.tandfonline.com/doi/abs/10.1080/14786447308640909

http://www.matematicasvisuales.com/english/html/geometry/rhombicdodecahedron/maraldi.html

See page 12 for cube illusion with rhombi:
https://www.jstage.jst.go.jp/article/forma/36/1/36_1/_pdf/-char/en
"Plane filling by the golden rhombus & the square-root-of-2 square rhombus" (Assumed 3d, not planar???)