You can also use a hollow plastic coffee stirrer. Hold the end of the stirrer in a plastic prescription pill bottle... bingo... something that sounds like clucks!
For those times when you don't want to take an expensive trumpet or wingbone call somewhere, the coffee stirrer will keep your embouchure in shape!
You can also use a cheap plastic ball-point pen (minus the ink and point!
Try 2 coffee stirrers and its a bit louder!