[math-fun] Möbius-band-made-of-squares puzzle

Some time ago I posed the puzzle: What is the smallest number of congruent (2-dimensional) squares one can place in 3-space, so that any two are disjoint or else intersect on a common edge or vertex, such that their union is topologically a torus with a disk removed? (The answer was 5.) This puzzle has the very same rules, except that the finished product is to be a Möbius band: ----- What is the smallest number of congruent 2-dimensional squares that can be placed in 3-space, so that any two are either disjoint or else intersect in a common edge or vertex, such that their union is topologically a Möbius band? ----- —Dan