In cross-section, what shape should an imping needle ideally be?

The ideal shape for an imping needle in cross-section is triangular. This design allows the needle to effectively penetrate the bone when imping the feathers onto a bird's wing. The triangular shape provides an efficient cutting edge and stability during the process, making it easier to secure the feathers properly.

A round shape would not offer the necessary cutting surface for piercing, while a square shape could create excess trauma to surrounding tissues. A flat shape lacks the structural integrity required to hold the feathers firmly in place. Therefore, the triangular cross-section is optimal for achieving a secure and clean placement of feathers during the imping process.