[janovrom]

Thank you for the extensive answer. It did not occur to me, that simple cast to RenderablePrimitive would give me access to the object input layout. During testing it I found out, that a DXMeshGeometry3D with input layout type Position | Normal | TextureCoordinate was rendering correctly (eye-balling it) with RequiredInputLayoutType = Position. 

Is there some additional collection step after applying the material? For example in the case above, is there a check if at least the position is present and if so, it will create buffer from these positions, or just binds the whole vertex buffer with a stride for positions. Is RequiredInputLayoutType strict requirement, or is there an issue only in case where you have for example required layout with TextureCoordinate, but the mesh created was SimpleMesh<PositionNormal> (it's not possible to bind to anything).