Step 2: Painting the bucket
The oscilloscope illusion results from watching a vibrating, black string against a background of alternating light and dark lines. We'll need to create a black cylinder with white, vertical "pinstripes."
Paint the Bucket: Flip the bucket upside-down and paint the outside completely black with spray paint. (Make sure that you use a paint that's recommended for use on plastics.)
Add the Stripes: Once the black coat is dry, paint twelve evenly-spaced, white "pinstripes" around the sides of the bucket. Masking tape makes for super-straight lines; aim to make them about 1/8" thick.
To help place the lines, I first made twelve white dots in a clock-face arrangement on the "bottom" (now "top") of the bucket, then used these marks as a guide when adding the tape and paint.
While the white stripes dry, move on the to next steps.