Hi there
I've made a CAD drawing of the housing for the Audiomoth, which can be exported to a STL file for 3D printing, as well as drawings of the gaskets. The housing is two pieces rather than 4, so if you use it, you'll only need the one gasket, rather than 3. The gaskets: https://cad.onshape.com/documents/a9a95cd9a59abcb6024d6400/w/684d9b044f1ac021b341b038/e/16491f34d189aebff4e7ccb7 The housing:
https://cad.onshape.com/documents/f2a7716c1aee0c2efec30e17/w/16cd33fcd57e9390832a3f53/e/92d396efb199ed6c0ad1a795
I sourced all my hardware from RS Components. Not the cheapest, but they allow small orders