Buckle

All credit goes to @lupi_1919561

A simple buckle is a versatile fastening accessory used to securely connect straps, belts, or bands. It is lightweight, durable, and easy to use, making it ideal for bags, backpacks, clothing, and various DIY projects. Perfect for quick adjustments and reliable fastening in everyday applications.

For an optimal printing experience, I recommend printing the female part upright, standing, and with supports. Additionally, PETG is certainly a good choice due to its well-known strong properties.