today, one of my friends brought in an old puzzle that was a bunch of yellow and red cubes attached by a single string. Does any one know what this is called? It's supposed to form a cube when solved
I have two puzzles similar to what you are describing:
They form a 3x3x3 cube, and each segment has connections at two sides, at either a right angle or straight through. Each connection can rotate freely, and the string connecting them is elastic so you can work with it. Here's some cell phone pictures, perhaps this what you mean?