A 3D printable triangle. Use different materials and different print settings to get different sounds.
We created a musical triangle shape, it was as a result of a request. We are not too sure about the musical part but you can have fund changing the material and printer settings to get different sounds.
We also added a tutorial on how we created it in Freecad using it's sweeping function where you extrude a 2 dimensional shape along a path to create a solid ( https://www.idig3dprinting.co.uk/shop/models/3d-model-of-triangle-musical-instrument/ ).
So why not have a go yourselves, follow the tutorial and see what you can make.