Elsa could create a lot of things out of ice and snow.
She could make snowmen, ice rinks, ice skates, tables, fountains, stairs, chandeliers, whole castles really, slides, bridges, and more. Anything her mind could imagine, her powers could conjure.
But there was one thing she could not-would not, create.
Anna once spent an entire day begging, pleading, and coaxing Elsa into making a certain something, but the Queen was resolute.
"What's the harm?" she would ask.
"I know you could do it," she'd encourage.
"Why don't you want to make one?" she would eventually wonder.
And Elsa wouldn't have the heart to tell her, for whatever reason.
Couldn't tell her that the reason she did not want to try her hand at creating life-like ice sculptures (of animals, of people, of her) is because she'd already created the most realistic ice sculpture the world had ever seen.
And she never wanted to do it again.
A/N: Just a headcanon that bounced into my head and refused to leave.
It's my opinion that after accidentally freezing Anna and turning her into a frozen statue, Elsa would be a bit put off about even thinking about Anna-shaped ice, even if she knew it wasn't actually her sister.