Wow! And a maths lesson in there too!I was doing my teacher training at Sussex University in the seventies and decided to take a white plywood model of a regular icosahedron* from the Resource Centre to my placement school at Three Bridges. I lived in Hove and so caught a rush-hour 4VEP. It just fitted through the slam-door, and sat on my knee for the half-hour journey, much to the amusement of fellow passengers.
* if you're interested: a regular icosahedron is a convex polyhedron made up of equilateral triangles with 20 faces, 30 edges and 12 vertices. It is one of the five Platonic solids, and the one with the most sides. It has five equilateral triangular faces meeting at each vertex.
Was it heavy? I assume it may not have been, being plywood.
-Peter