Noise-making apparatus and method

A method of metering a flow of compressed gas, the method comprising:

• obtaining a pneumatic engine comprising
• a body comprising a first chamber having an exit aperture, a second chamber having an entrance aperture, and a bolt aperture connecting the first chamber to the second chamber,
• a source delivering compressed gas to the entrance aperture, and
• a bolt positioned within the bolt aperture and extending into the first chamber and into the second chamber, the bolt comprising a conduit placing the first chamber in fluid communication with the second chamber;
• and
• cycling the pneumatic engine, the cycling comprising
• releasing the bolt to move as biased,
• driving, by a first quantity of compressed gas contained within the first chamber, the bolt in a first direction to unblock the exit aperture,
• venting of the first quantity of compressed gas out of the first chamber via the exit aperture,
• compressing, by the bolt as it moves in the first direction, gas in the second chamber to generate a second quantity of compressed gas, and
• driving, by the second quantity of compressed gas, the bolt in a second direction, opposite the first direction, to block the exit aperture.