When evaluating aluminum cases, prioritize the grade of the aluminum alloy (typically 5052 or 6061) for the outer shell to ensure a balance between lightweight portability and high impact resistance. The internal padding should consist of high-density EVA foam or plush-lined EPS, custom-molded to the specific instrument shape to prevent movement. Additionally, check for reinforced steel corners, heavy-duty recessed latches, and spring-loaded handles that can withstand the rigors of professional touring.