Ben Affleck took Violet and Seraphina to a do-it-yourself fashion design store for kids in Santa Monica, on Sunday. And the girls emerged looking like hot stuff!

They were so cute, in fact, dad Ben desperately wanted to get a shot of the girls to send back to mom Jennifer Garner, at home, but to no avail ... apparently Violet and Sera are designers, not models!

Seraphina designed (and donned) a pink puffer vest and skirt, while Violet chose to decorate a shoulder bag. So cute!