Air-sensitive 2D materials present a fundamental challenge for device integration. Encapsulation is often required to preserve intrinsic properties, yet conventional protection strategies often fail for thicker layers and complicate fabrication. Here, we demonstrate that electron-beam (e-beam) evaporated aluminum oxide (AlOₓ) serves as both an effective encapsulation layer and a platform for direct device fabrication. Unlike transfer-based approaches, this scalable method is compatible with thicker flakes and full device or wafer coverage. It requires no stacking procedures and enables contacts without post-encapsulation etching. Using rare-earth tritellurides (RTe₃, R = La, Er), semimetallic WTe₂, and superconducting FeTeₓSe₁₋ₓ, we show that AlOₓ suppresses oxidation and preserves intrinsic optical and electronic properties. We establish substrate-dependent optimization of encapsulation across a range of flake thicknesses, demonstrate that ultrathin AlOₓ preserves WTe₂'s plasmonic response and maintains superconducting performance in FeTeₓSe₁₋ₓ. Thus we overcome the longstanding tradeoff between encapsulation and straightforward device fabrication in fragile quantum materials.