Making DIY landing gear for quadcopter, hexacopter or tricopter using cupboard door lock (aka drawer lock). They are designed to prevent little children from opening the drawers and cupboard, which might contains dangerous items such as knife and glass. And they are widely available on ebay. But some smart people adapted them and use them as durable and affordable landing gear solution.

just install it at the bottom plate of your quad, cheap and practical solution! Here is an example.

Tip from OpenPiot forum.