My family has been breaking teapot lids for generations: My grandma did it, my mom did it, and I do it. And the last time I did it, I decided to make a more durable replacement. 

Suitable for teapots with D-shaped openings, I have made it to fit my particular generic white teapot. Probably, you can scale it for yours! 

Print in temperature-resistant filament, upside down, with supports. If you are actually going to eat off of it, coat it in food-grade resin.