This is a very cute little trick. The solid yellow silk can be replaced with the duck/rabbit silk
for an interesting variation, you can check magician Christopher Hart in Youtube for his routine.
The inclusion of a non gimmicked duck to switch for the one with the hole and pass it to be examined
is a very good idea. I love this trick! It's great for little children, and even adults get a kick
out of it if it is performed as a wah wah wah trick! LOL!