Sometimes we go crazy looking for our keys
We just need patience and skills
Let alone the bottle cap.
I use this system to set the bottle cap but you can use another. (How i use in the next option)
Set on anywhere
Make a little hole in the middle of our bottle cap
The string passes through the hole
You can cut the ends of your string
And finally set it wherever you want
Paste bottle cap to a door sticker (you can find at any hardware store)
Paste wherevere you want
Funny and creative way! If you liked i have more hack home inventions. I apologize for my english!