USELESS MACHINE · 4.5 V
CIRCUIT M 3 × AA4.5 V +− DPDT toggle onoff limitswitch 0.0 Vstopped

The toggle is a DPDT switch wired across a DC motor. Flipped on, it sends the battery to the motor one way and the arm rises. The arm's pin pushes the lever back over centre, which reverses the motor through the limit switch. The arm retracts until it sits on the limit switch's leaf, which opens the circuit and stops it. Front and right walls removed; the lid, mechanism and battery pack separate along the vertical axis.