Dan Alderson once made a map of nearby stars by mounting little colored spheres on threads strung between holes in two sheets of heavy clear plastic.

It occurs to me that, taking the stars in pairs, he could use half as many threads; each would be oblique and therefore longer, but none would be twice as long as the straight threads.

Such a design would be error-prone in execution, and thread is cheap. But I think Dan would chuckle at the suggestion.