Well, I use an actual bowl or glass, just mold the fondant with some gumtex added to it at the rate of about 2-3 tsp. per 10 ounces of fondant or so. I tend to mold to the inside of whatever I am using. That is when I use Wilton fondant which already has a hardener added to it. Or use prepared gumpaste. But fondant on its own will not harden up enough to be really durable for this purpose. I tend to use a dowel in the stem part so that I can attach the stem to the bowl part of the glass and allow it to dry that way. You don't have to if you use a mold for the stem or have a way of drying it where it will not flatten out on one side.
to make a lid for you bowl, well wait for the bowl to dry, then turn it upside down and mark out a circle that size. That should give you the perfect size for a lid as it will be big enough to sit on the rim of your bowl.
I do plates and saucers the same way, turning a real saucer or plate upside down and tracing a circle just a bit bigger. Then I place it right side up on top of the saucer or plate and press down so that I can get the indentation of the rim of the saucer or the rim of the plate.
Here is a picture of a plate I did to match a real coffee mug.