The Julius Caesar Costumes and the Psychedelic 60s Lady rank as my some of my favorite Jack Kirby Costume Designs. I wish they made a statuette of the Lady with the Big Hat because I would love to see how that works in three dimensions. Or at the very least learn more of the story behind her!
Haven't heard of anything, but you know several years ago, a sculptor worked with Kirby on Jacob & The Angel (the one that makes the brain go "boom"), and that was quite amazing to see. Sometimes, there is no story behind Jack's "art for fun" stuff, but I suspect it's mainly because we didn't get the chance to ask him. If he were here now, and you asked him the story behind the Lady with the Big Hat, he would probably pause for a moment, chomp and swirl an unlit cigar, and start telling you some amazing tale that would rival Galactus and the Silver Surfer. Da King! (what is it with you and Jack's characters with Big Hats? If you haven't seen Big Trouble in Little China, you must check it out...great Big Hats)