Start with a point.
Make a copy of the point, and move it some distance away. Connect these points. We now have a segment.
Make a copy of the segment, and move it away from the first segment in a new (orthogonal) direction.
Connect corresponding points. We now have an ordinary square.
Make a copy of the square, and move it in a new (orthogonal) direction.
Connect corresponding points. We now have a cube. Make a copy and move it in a new (orthogonal, fourth) direction. Connect corresponding points. This is the tesseract.
So there.