Step 1: Obtain high-contrast templates
Print the file, and cut out the images. Warning: this will use a lot of black ink.
Step 2: Prepare wire hangers
Step 3: Tape the hanger legs
Step 4: Twist and tape the top of each hanger
Step 5: Combine the hangers to form the mobile structure
I also straightened out the hook parts, twisted them together and taped them up.