The ConvexMeshShape class can be used to describe the shape of a convex mesh.
In order to create a convex mesh shape, you first need to create an array of PolygonFace to describe each face of your mesh. You also need to have an array with the vertices coordinates and an array with the vertex indices of each face of your mesh. Then, you have to create a PolygonVertexArray with your vertices coordinates and indices array. You also need to specify your array of PolygonFace. Then, you have to create a PolyhedronMesh with your PolygonVertexArray. Once this is done, you can create the ConvexMeshShape by passing your PolyhedronMesh in parameter.
r3d.ConvexMeshShape.new creates a new collision convex mesh shape