Bendable/Weldable Aluminum

A tricky question.

Depending on what you want to do with it, you might consider the type aluminium pipe used for automotive and other AC systems.

In principle, most aluminium, considered, having the right equipment and fill material, is weldable.

For extra soft aluminium it might pose a problem close to the welds, since the composition will result in a more hard area around the weld after time.