Different　from　the　classical　periodic-resonator-based　metamaterials,　epsilon-near-zero　(ENZ)　metamaterials　provide　a　unique　paradigm　to　achieve　equivalent　electromagnetic　characteristics　in　deep　subwavelength　scales,　exhibiting　unprecedented　impacts　on　a　broad　variety　of　extreme-small-volume　applications.　By　doping　regular　dielectric　rods　in　the　ENZ　host,　the　effective　permeability　µeff　of　ENZ　metamaterials　is　properly　tuned　for　desired　scattering　properties　and　intrinsic　impedance.　However,　losses　in　ENZ　metamaterials　severely　limit　the　tuning　range　of　the　real　part　of　µeff　and　result　in　an　undesired　imaginary　part.　Here,　to　mitigate　the　loss　issue　of　ENZ　metamaterials,　a　dielectric-free　approach　is　theoretically　studied　and　experimentally　verified　by　substituting　dielectric　dopants　with　metal-layer　dopants　to　construct　a　low-loss　resonant　cavity.　Therefore,　the　largest　tuning　range　of　µeff　is　achieved,　which　advances　ENZ　metamaterials　from　ideal　cases　to　more　extensive　and　practical　applications.　In　addition　to　existing　photonics　and　electronics　applications　of　regular　ENZ　metamaterials,　additional　examples　are　studied　to　demonstrate　the　low-loss　benefits　of　layer-type　ENZ　metamaterials,　including　integrated　microfluidic　switches　and　high-sensitivity　sensors　with　a　sensitivity　of　11.2%　and　quality　factor　of　2800.　These　examples　reveal　universal　significance　for　wide-range　applications　in　extreme-small-volume　devices　and　systems,　such　as　integrated　circuits,　chips,　and　implanted　devices.　©　2023　Wiley-VCH　GmbH.