You don't need a 3-D printer or electronic circuits to make a working timepiece. You can use materials from around the house while you're in isolation to build a timepiece whose invention goes back thousands of years.

The second-oldest form of timekeeper (Q: What was the first? A: The Sundial) was the water clock. As water dripped out of a hole from one container to another, marks on one of them would measure how much time had gone by.

The Ancient Greeks called it a clepsydra, which is often translated as "water thief," over 3,000 years ago. According to some sources, the Chinese version of the water clock may be even older. Some versions used floating figures in the water to point to the time.

This water clock is very easy to make. Depending on the size of your container and how large a hole you make in the cap of the bottle, you can create a 3-minute timer, an hourglass, or a water clock that will last all day.

Supplies

You need...

A clear plastic water bottle or drink container (I used a 1-liter flavored water bottle. One without ridges will be easier to see into)
a pair of Scissors
Masking tape
Marker
Timer or Stopwatch
Ruler (optional)
Food Coloring (optional)

Step 1: Prepare Your Bottle

Make sure the bottle you will use is clean and dry.

I left the label on the bottle until it was cut. That way, it gave me a guideline for the scissors.

Use the scissors to cut around the bottle. The cut should be a little above the half-way mark. For a 9-inch bottle, I cut it at the five-and-a-half-inch mark, which happened to be a level of the label that I could follow. The top section needs to be shorter than the bottom section.

Once the bottle is cut, remove the label and clean off as much of the adhesive as you can (You want it to look neat and pretty, don't you?).

Step 2: Make the Water Hole

Remove the cap from the bottle.

Make the hole in the cap from the inside to the top of the cap. Try to get it as close to the center of the cap as possible.

REMEMBER: the size of the hole you make will determine how fast the water will flow through your water clock.

Put the cap back on the top of the bottle...tightly, so it won't leak anywhere but the hole you made.

Step 3: Begin Your Test Run

Plugging the hole in the cap with your finger, fill the top section of the bottle. Don't fill to the brim, or you may spill water as you try to carry it toward the bottom section.

Holding the top over the bottom, start your timer or stopwatch at the same time as you take your finger off the bottle cap hole.

Set the water-holding top onto the base section, and watch time fly.....or crawl.

Step 4: Marking Time

As the water drips, dribbles, or pours from the top to the bottom, watch your watch or timer. You want to measure and mark the elapsed time. You may be surprised by how fast or slow the water runs out of the top. Do not use a marker until you know if you want to mark seconds, minutes, hours, or some other measurement.

I suggest using small strips of masking tape. Stick them to the side of the bottle at the water level of each time measurement.

When all the water runs out of the top...Stop Measuring!

Step 5: Finishing Your Water Clock

If you aren't happy with the speed your water clock runs, you can change the size of the hole in the cap and re-calibrate. If it's too slow, enlarge the hole by twisting th scissors in the hole. If it's too fast, take a cap from another bottle, and make a hole in it that is smaller than your first one.

Cut a strip of masking tape, longer than the distance from the lowest of your marks on the bottle to the highest. Put it next to your tape marks. Use your marker to draw lines on the vertical tape matching the levels of your time marks. Whatever units you used for measuring, mark the numbers at the lines.

Now that your clock is made, you can use it as an emergency clock when the power goes out...or not.

Have a good time!

Step 6: Notes:

To Make the Water Level More Visible: Add a few drops of food coloring If the water is colored, you might clean the bottom container before each use, to avoid discoloration.

Truth in Advertising: I re-made this and re-made this. The first time, it took 4 minutes to empty. My second try was a 50-minute model. My third version, which used the 50-minute cap with a wider hole, is my 7-minute model. Some of the pictures were staged to show better levels of water.