Robustness　of　microcapsule　shells　determined　the　service　life　and　application　areas　of　final　smart　materials　including　self-healing　composites,　anticorrosion　coatings,　smart　concretes,　and　so　on.　Herein,　we　designed　and　synthesized　metal　microcapsules　by　conducting　electroless　plating　directly　on　liquid　droplet　surfaces,　and　metal　shells　showed　superior　stability　in　thermal　(600　degrees　C)　and　polar　solvents　(acetone　and　N,N-dimethylformamide)　environments.　More　interestingly,　the　mechanical　strength　of　metal　shells　was　ten　times　higher　than　those　of　all　published　microcapsules.　Besides,　the　smart　epoxy　composites　remained　stable　mechanical　properties　with　metal　microcapsule　concentrations,　and　this　is　the　first　time　to　report　such　results.　For　engineering　materials,　mechanical　properties　played　an　important　role　in　practical　applications,　and　a　higher　strength　usually　accompanied　with　better　safety　and　longer　service　life.　The　microcapsules　with　designable　structures　could　be　synthesized　by　adjusting　shell　thickness　and　core　fractions　for　practical　requirements.　The　metal　microcapsules　had　great　potentials　to　be　applied　in　a　smart　metallic　matrix,　conductive　multifunctional　materials,　and　pH-responsive　materials.　In　addition,　the　electroless　plating　technique　was　also　first　applied　to　liquid　surfaces　pushing　the　development　of　novel　smart　materials.