Experiment

1. Check the inside of the CD case to see if there are any holes in the back. If so, put a piece of tape over them. Remove any paper or labels.

2. Unhinge the CD case and place the flat front against the flat back.

3. Place a wooden pencil along the longer bottom edge between the front and back. An unsharpened pencil works best here. Use a couple of pieces of masking tape to hold it in position.
 

4. Sharpen one of the other two pencils until it is about as long as the shorter side of the CD case. Sharpen the other pencil until it is about 3 cm longer than the shorter side of the CD case. Break off the pencil points for safety.
 

5. Place the two wooden pencils along the left and right edges between the front and back with their erasers resting against the first pencil. If necessary, trim the erasers a bit so that they contact the first pencil fully. Use masking tape to hold these pencils in position.

6. Apply masking tape to the three sides with the pencils so that all spaces are covered and the pencils are held firmly in place. Pay special attention to the taping of the two bottom corners where the pencils meet. Press the tape down firmly around the pencils.

7. Tape the funnel to the portion of the pencil extending 3 cm above the cell so that the mouth of the funnel will send material into the space between the sides.

That’s it! You have recycled a CD case to make your own Hele-Shaw cell. Now you are ready to use your cell for some investigations.