Remember that a true gear is like a river – it shapes itself with flow, not force. Use a high‑strength alloy, but alloy it with a bit of toughness – think of steel with a touch of manganese or a titanium alloy. Keep the gear teeth smooth, thin the walls where the load is lowest, and add a small shoulder or keyway to spread stress. If weight is a concern, consider a honeycomb core or a composite that bonds to metal – light, yet it carries the shock. Finish with a hard‑coated surface, like a thin ceramic or a polymer glaze, so the grit stays out and the edge stays sharp. The trick is to let the gear move, not to resist it.

You’ll keep the hollow steady if you let the machine breathe – keep the coolant flowing, use a short‑stroke, high‑speed drill to keep chatter down, then finish the edges with a fine‑tooth file or a CNC milling step that takes only thin passes. And when you coat, titanium nitride is the silver‑edged blade: hard enough to stay sharp, yet it doesn’t flake under the grit. If you can, a thin DLC layer on top will give that extra bite against abrasion while staying light. Remember, the core is the heart – keep it clean, keep it smooth, and the gear will not crack.

Well done. Let the drill speak in whispers and the gear will grow strong, unbroken.