Identify a familiar space homeomorphic to each of the following constructions, and prove your answer geometrically.
The mapping cylinder of \[ f:I\to S^1,\qquad f(t)=(\cos(4\pi t),\sin(4\pi t)). \]
The mapping torus of \[ f:S^1\to S^1,\qquad f(x,y)=(x,-y). \]