Jenny Mathison-Foster stumbled across a love for millinery, or women’s hat making, when she discovered the intricacy of the process about 20 years ago, she said. In September 2015, Mathison-Foster opened Bay Willow Design in downtown McKinney. Bay Willow sells ready-to-wear hats and makes hats to order. “I am a little bit different than all the rest of the stores downtown,” Mathison-Foster said. “More of my business is custom [orders] than people buying from the shop.” Bay Willow’s custom-client base varies, Foster said. Some customers need extravagant hats to wear to the Kentucky Derby or to Mad Hatter tea parties, while others order more casual hats to wear day to day. Mathison-Foster, whose background is in fabric design and art history, said millinery is a way to use all her knowledge and express her creativity. She said she has the tools and materials to make hundreds of hats in different sizes, shapes and colors. “There is so much you can do with hats for women; it’s crazy,” she said. “Almost everything I do is hand-sewn.” Bay Willow is both a shop and Mathison-Foster’s design studio. She said a great thing about a shop connected to a studio is having clients come in, try on different hats and find the perfect style for them. “A hat changes your attitude; it changes your look; and it changes who you are,” she said. Bay Willow expects to undergo renovations this summer. Foster said she is planning to remove the dividing wall between the shop and studio. She hopes this will make the space more welcoming to customers who would like to learn more about the hat-making process.