What device should be used to secure the pieces of the assembly and ensure they remain aligned?

Using spring clamps to secure the pieces of an assembly is the preferred choice due to their design and functionality. Spring clamps provide a stable and adjustable grip that can hold components tightly together without damaging them, which is crucial in aerospace applications where precision and integrity are vital.

The springs in these clamps exert constant pressure, allowing for easy adjustments to accommodate various sizes and shapes of parts while maintaining alignment during the assembly process. This is particularly important when working with intricate assemblies where misalignment could lead to significant issues down the line, such as structural weaknesses or improper fit. Spring clamps are also quick to apply and remove, making them efficient tools for assembly tasks.

In contrast, other options might not provide the necessary stability or alignment. A tape measure is useful for measuring but does not hold pieces together, while vise grips are designed for gripping stationary objects rather than aligning parts during assembly. Rubber bands lack the clamping force required to securely hold parts together, especially in high-stress aerospace applications. Thus, spring clamps stand out as the most effective solution for ensuring parts are aligned and securely held in place during assembly.