I got a round cake style silicone pan from Kmart, and just cut the sides out and used them for silicone washers
smooth side towards the keggle/pot for better sealing, and using a washer helps as well
I used a 6 cup muffin tray and cut the hole out the bottom with the bulkhead then used te washer for the outside. I then used the sides of the cups for other washers.