I’m building four of the Kevin Rodel Arts and Crafts Side Chairs shown in the FW March/April 2007 magazine. I’ve never upholstered much of anything before but wanted to try my hand on the slip seats for these four chairs. The slip seats are approximately 18”x16 1/4” with a 3/4” wooden seat frame. I plan to use leather to upholster the seats as shown in the FW plans. How much of the leather should I purchase to complete the four seats?