Trebuchet

import { createAsset } from 'https://gaitkit.com/cdn/trebuchet.mjs';

const trebuchet = createAsset();
scene.add(trebuchet);                      // rests on y = 0, front faces +Z

// 'arm' pivots on its hinge: -34.5° to 118° around x
trebuchet.getObjectByName('arm').rotation.x = THREE.MathUtils.degToRad(-34.5);

import { useMemo } from 'react';
import { createAsset } from 'https://gaitkit.com/cdn/trebuchet.mjs';

export function Trebuchet() {
  const model = useMemo(() => createAsset(), []);
  return <primitive object={model} />;
}

# Import trebuchet.glb (download below). Moving parts are separate nodes, pivoted on their hinge.
$Trebuchet/arm.rotation_degrees.x = -34.5

// Import trebuchet.glb with glTFast (com.unity.cloud.gltfast).
transform.Find("arm").localEulerAngles = new Vector3(/* x: */ -34.5, 0, 0);