It's simple. First, prepare a small tool knife and draw a cross on the bottom of the mineral water bottle. This cross is the size of the bottle cap. Then press the bottle cap firmly from the bottom. The effect is the same as going directly from the bottom. Another way is to find a mineral water bottle with wrapping paper, first remove the paper intact, and cut a piece with a tool knife, so that two fingers can put the bottle cap in obliquely. Tilt the bottle cap in the bottle. It's best to get stuck on the bottle (bottles are round and can usually get stuck). If it can't get stuck, screw it with glue. Stick the wrapping paper back. You can't see the bottle cap inside from the outside. It's best to find the same bottle cap and fill it with water. Drink water first. Take off the bottle cap. Then take the bottle cap in your right hand and the bottle in your left hand. Knock hard with your right hand and the bottle cap inside will fall off. Then you can find a way to make the bottle cap disappear in your hand.