When there is a lot of confusion, it is best to go to the source. In this case, confusion over baby rattle specifications are easily resolved by reading the government regulation specifications in section 1510.4. The regulation provides measures for a test fixture. If a rattle passes the test fixture, it is legal. The test fixture is a minimum requirement – a rattle can be larger as long as any piece does not protrude to the other side of the fixture.

I also want to engrave the handle of this baby rattle. The difficulty is that the laser head must clear the highest point of the rattle. At this height, the handle is out of focus. The engraving would be horrible. The solution is to make the rattle in multiple parts that can be attached after the engraving.

Others have used a wide variety of objects inside the rattle to make the noise. The problem is that the wood deadens much of the sound – A jingle bell just does not sound like a bell. I chose, instead, small ball bearings that yield a nice percussion sound that works well with the wood to resonate.

A 3D printed test fixture for rattles can be downloaded from Printables at:
https://www.printables.com/model/1789355-baby-rattle-test-fixture

My formula for beeswax and mineral oil:
.25 pound beeswax chopped
1 pint mineral
Combine and heat in a double boiler, stir until mixed. A shortcut is to put in a container into a hot attic or a hot car. Stir daily until mixed.

This rattle is 1.5″ by 5.5″ finished with beeswax and mineral oil.

Enjoy.

If you happen to have technical difficulties, this video is also posted on YouTube. But it is best right here. So stick around.