Nesting trays

Trays that nest inside each other, and also stack vertically (even when nested).
The trays are designed with a 0.4mm gap between them when nested.

Nearly all dimensions are parametric in the [OnShape CAD document](https://cad.onshape.com/documents/d7ac354e618862f00d0a6240/w/5704c827d007da8888690675/e/59a1c51f19483c277032424d?configuration=List_p7h76IO9C0jnHi%3Dnesting_250_4%3Bmax_overhang%3D0.8726646259971648%2Bradian)