Grave Robber's Crypt - Crank-Driven Halloween Automaton

Turn the crank and the crypt wakes up. Over one slow turn the iron gate creeps up, a skeleton hand rises on its lever just before the gate drops fast, and a bat swings past the moon on the side wall  then it all resets for the next turn. The roof lifts off and the back chamber holds candy.

It's a single shaft machine: two gate cams, one hand cam, and a bat crank all ride one crankshaft, keyed with D-holes so the timing stays put (crank counter-clockwise seen from the right). Gate lift is about 13mm per turn; the hand rises about 20mm and drops roughly a quarter turn before the gate.

Print: 0.4mm nozzle, 0.2mm layers, 3 walls, 15% infill, PLA, no supports. Print the test gate first it has to pop free and slide in the body's gate pocket; if it fuses, run a thin blade around the pocket gap before printing anything else. Shaft prints flat side down, sleeves print upright, roof at 5–10% infill. Pins are 1.75mm filament offcuts (about 16mm, 13mm, 8mm, 8mm) with the ends mushroomed using a lighter.

Assembly: shaft goes tail-first through the left wall with the knob outside left, then long sleeve, gate cam, short sleeve, hand cam, short sleeve, gate cam, long sleeve through the right wall. Every cam and the bat crank go on with the printed-top face toward the right wall flipped and it runs backwards. Gate tabs rest on the gate cams, the lever sits between the uprights with the hand end forward, and the rod links the crank to the bat arm.