Detail this asset from Unity Asset Store: Original Link
This is a paid asset, but now you can download Mesh Slicer Free.
Mesh Slicer v2.0.7 (Latest version)
Mesh Slicer v2.0.6
Mesh Slicer v2.0
“If possible, please buy the package to support the developer”
– Synchronous/Asynchronous slice;
– Slice meshes with colliders converting BoxCollider, SphereCollider and CapsuleCollider to MeshCollider;
– Skinned mesh support (beta version)
– Easy to extend;
– Very fast algorithm (just take a look at reviews);
– Smart optimization. So after slice you will not see any redundant triangles or vertex due to slice;
– Slice by plane;
– Slice by knife (examples).
The game that uses this asset (android): BeSlicer
You can try it for free here. This is fully featured mesh slicer, but with no source code (dll-s only). And it will not work in release mode more than one minute.