Guitar Strap Clip
This clip allows you to attach a guitar strap to the neck of an acoustic guitar. My guitar had the button on the bottom but was missing any attachment point at the top, so I designed this. It slides on and off easily, but stays in place while on. It also has a built in pick holder.
Works well on my Yamaha, not sure about other guitar models. The important part is that your guitar must have at least 6mm clearance between strings and head.