Puzzle

When I was at school, inspired by a book on symbolic logic in which I found the design, I made myself a toy. It consisted of several cardboard triangles. One was marked with a hexagonal grid containing various combinations of a, b, c and their opposites (~a and so on). I remember the extremities of the grid, at the points of the triangle, were the states in which only one of the elements is true (a ~b ~c and so on). The other triangles had various combinations of holes cut out of them and each one represented a different logical operation, one which would result in the states revealed by the holes. I remember this thing quite distinctly, though not how to rebuild it, quite.

I can't remember what it's called.

And it's bugging me.

I don't have any use for the thing at all (I'm not even sure what use if any it is) but till I know that it actually exists and has a name I can't let go of it. If anyone can tell me what it is, where to find it on the Web or even just that they read the same book, I would be so very relieved.