In this instructable I will walk you through the process of how I make a cartesian diver, or a bottle diver.
The cartesian diver uses pressure (exerted by you) to make the diver sink and rise based on the amount of pressure applied to the water bottle.

Step 1: Supplies

I have assembled a list of supplies that you will need for this project, feel free to skip ahead and see how it's made.

1) 1/2 inch smoothie strawd
2) permanent marker
3) lighter
4) BBS
5) sissors
6) needle nose pliers
7) ruler or measuring devise
8) water bottle or empty 2 liter bottle

Step 2: Prepare Straw

My straws were none inches long, so I cut them in three inch increments, or 7.6 cm peices. Easily mark the measurement with the marker before cutting for precision.

Step 3: The Build

Now you can assemble the diver, start by crimping the end with the pliers, and then heating/ melting the end shut with a lighter. Make sure you have not holes so air can't escape.
Full the straw with exactly ten BBS, and then deal the opposite end.
Done! Now drop your diver the bottle full with water, cap it and squeeze!

Step 4: Final Thoughts

These toys are great for explaining pressure in chemistry, or for just showing off at parties.
Thank you for checking out this instructable, and if you liked this one, you may like my others, so be sure to check those out too.
More to come!