Tennis Balls in a Bottle (How-to!)

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Introduction: Tennis Balls in a Bottle (How-to!)

About: I got an old sewing machine when I was just a kid, and I've been hooked on making stuff ever since. My name is Sam and I'm a community manager here at Instructables.

I love a good puzzle.

Some of my favorite kinds are strictly conceptual, meaning that once created, these objects require you to simply look and think about them. You can hold them, shake them, examine them . . . but you can't physically disassemble the completed object.

I have several such items at my house that just sit on a shelf and cause visitors to scratch their heads and say ". . . wait . . . how did you . . ?"

Spoiler Alert:

In this instructable, I'm showing how I put two standard tennis balls into a completely unaltered bottle.

For any readers that enjoy puzzles and are up for a challenge: stop reading, examine the photo above, and try to duplicate it on your own. To you brave souls, I bid you good luck and happy problem-solving; come back when you've got it and let me know how it went!

For everyone else, read on to see how I did this.

Step 1: Bottle and Balls

The bottle I'm using is a carafe I got at a local thrift store for 50 cents. The narrowest internal part of the neck is about 1 5/8" (4.1 cm) in diameter.

The balls are standard tennis balls and are about 2 5/8" (6.6 cm) in diameter.

Step 2: Considerations

I encountered some funny things as a result of the fact that I used generic Walmart tennis balls for this.

From whatever manufacturing process is used to make these tennis balls, they're left with these little flaps on the rubber seams which distract people into thinking something is amiss where there really isn't. Also, the lack of any branding or logos leads people to think these tennis balls are "trick balls" or something, which they are not.

Because of this, I recommend using higher quality tennis balls for the sake of presentation. Whatever tennis balls you use will work exactly the same, however.

Step 3: Cut

Use a sharp hobby knife to make a 1/4" incision in each ball.

Note that when you press the ball a certain way it opens up. When you release, the cut disappears.

Step 4: Fold

On the opposite side of the ball from the incision, press that half of the ball inward to create a bowl shape.

Then fold the ball in half as shown. It's critical that the cut be facing outward at this point.

This may take some effort and ninja-like grip strength.

Step 5: Wedge

The ball is now wedged into the bottle.

Compress the ball as much as possible before you begin to wedge it in. With a moderate amount of pressure the ball should plop down into the bottle.

If you're concerned that the bottle neck may break from the outward pressure of the compressed ball, you might want to wear gloves, long sleeves, and goggles. (I did not do this, but the thought certainly crossed my mind.)

Step 6: Wait

Because the cut is on the outside of the folded ball, it is being somewhat held open which allows air to return into the ball.

If you wait a few seconds the ball will re-inflate by itself.

If it does not, you can prod it a little with a long dowel until it does.

Step 7: Fluff

If upon close inspection the incision is visible, use a long wire with a bend on the end to fluff up the fibers around the cut to mask it.

This little implement was made from a straightened piece of wire with a couple of L bends on either end.

It is useful for many things.

Now just repeat the process for the second tennis ball.

Step 8: Done!

That's it!

It's seems simple and obvious . . . once you've seen how it was done. Can you think of another way you could do this, perhaps with a bottle with a smaller neck?

If you're up for a tougher challenge, check out my Deck of Cards in a Bottle instructable.

Thanks for reading!

3 People Made This Project!

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101 Discussions

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JimF93

1 year ago

When I got my advanced open water certificate (scuba), the instructor did something very similar, but I think with handballs. At about 110' of depth, the balls were totally collapsed, and fit into the bottle just fine. Same concept, but they balls were 100% undamaged. If one were to smash the bottle to get them back out (hehe, that's the easy way to recover them), those balls would have been completely usable. But any pressure chamber should suffice. At 110', I think we were at about 4.5 atmosphere (every 30'-33' of sea water adds another atmosphere).

1 reply

I'm sure you could get them back out again at 110 feet under water. For tennis balls, I imagine they'd wrinkle instead of contracting uniformly, so they'd still have to be squeezed. However, with the handballs, you could probably tape the ball over the top of the bottle, loosely, then attach it to a weight and lower it from a boat. You'd have to maintain that vertical position. If it turns out that the squashed handball still floats, you could do it upside down.

If I still lived in Vermont, I could go to an old granite quarry in Barre and just dangle it from the observation platform. Assuming the platform was still there, anyway.

what about using a ball inflation needle and then using a vacuum brake bleeding pump from Harbor Freight or other type of vacuum pump.

2 replies

A couple of people have suggested something similar, but I personally have not tried that approach.

In the end, I figure the simplest means to the same end is ideal . . but that can hinge on what tools you have available.

Maybe just make a tiny hole and be patient when squeezing.

It might work to put some water into the bottle, then drop in a couple of Alka-Seltzers and turn the bottle over.

Clever, but you might want to stay 20 feet back in case the bottle exploded instead.

0
user
kepeb

1 year ago

Two things I don't understand.

Why did you want the balls in the glass?

And how do you get them out?

2 replies

I think, for many people, once they got the idea they'd feel compelled to do it. Not sure I can explain that. Related to the reason Hillary climbed Everest. Maybe Tenzing Norgay had the same reason, but I think if you mention Hillary, it's good form to mention Norgay.

1. To make people wonder how you got the balls in the carafe.

2. You don't. That's not the point of the project. See 1, above.

I'm sure you could find suitable tools to cut the ball into little pieces. If you cut with a knife, it might help to put some soapy water in the bottle first.

Ok... So I shouldn't use any old, valuable museum vases then!

(not that I was planning to...)

Alternatively, just set them on fire, mwuahahaha. Of course, this may break your museum-grade vase anyway, but at least you'd get some pyrotechnical fun out of it.