A swiss roll tin is a large, flat tray with small edges. It's designed to make a thin cake, which is perfect for rolling. It's also known as a jelly roll tin. The one I used is from Dunelm and it measures roughly 35 x 25cm x 2cm-deep. Unfortunately, I can't find the online link for it but MasterClass sells an identical one online if you can't get to a Dunelm store. Any tin that's roughly 10 x 14" should work fine.