Tilly & The Button Arielle PDF £9.50
I also made an Itch to Stitch Lisbon cardigan with similar buttons. I ordered them on ebay (20 for £3.80). I used grey French terry and topstitched the seams with a zigzag stitch which makes all the difference for a traditional cardigan appearance. The difficult part was topstitching each side of the arm seams, which join nicely to the side seam stitching, and the pressed-up seam allowance on the sleeve cuffs took some manoeuvring.