It's great to see that this important instrument is being used in other parts of the world.
My first lagerphone was a bit like yours but made of a shovel handle for a bit more weight. The cross-bar had bottle tops on the top and bottom allowing these tops to bounce up and down on top of each other (no rude remarks please) and these seem to make more noise. I get much the same effect on my current one by the way the top part sticks out at an angle.
An alternative name for the instrument is the Murrumbidgee River Rattler.