This is for those who are in a hurry to create elf ears for themselves or their kids, and those who doesn't want to use clay, silicon etc. This is what I figured out for myself in the process, and my daughter was super happy with them.
Step 1: Find Photo or Draw
Locate an image of an elf ear online that you want to use OR draw & color the ears yourself.
Step 2: Duplicate and Resize
Duplicate the ear and resize the pair digitally, using for example Photoshop. No need if you drew them yourself in wanted size.
Step 3: Print Ears
Print the ears. No need if you drew the ears yourself.
Step 4: Glue Prints to Cardboard
Glue the prints/drawings to a piece of cardboard. Let dry, and then cut out the ears.
Step 5: Attach Rubber Band
Attach a small rubber band on the back, using a piece of tape mounted on the front part of the ears.
Step 6: Put on Your New Elf Ears
The rubber band will keep the elf ears in place. Enjoy!