Note: All interior pieces have the same basic shape.
From one source, this shape is called “regular”; see an image. There are two shapes that are obviously missing:
» those pieces with no “knobs” (or “bobbles” or male connectors) and
» those pieces with four “knobs” (or “bobbles” or male connectors),
as shown in the top image on this page at canstockphoto.com.
Retired economics professor (“dismal scientist”). Married 40+ years to the love of my life; we have two grown daughters, both married, two granddaughters and a...
![Sigh. [Travel-day]](https://media.365project.org/1/9428160_bfilmqru48_sq.jpg "Sigh. [Travel-day]")
