When you think of convenience think of single cup coffee machines. These have no carafe or thermos to catch the coffee that is made. You put your own cup under it and the coffee is brewed directly into it. The advantages are many. You don’t have to wait for a whole pot to brew if you want just one cup. Secondly the coffee never gets old sitting in a carafe. You always get a fresh cup of coffee whenever you want it.
There may be different makes and different shapes to a single cup maker, but the process would be the same. They also don’t need to have a warmer on them because the coffee never sits there. In single cup coffee machines the water is boiled and sent through a filter, which holds the coffee grinds. It is caught by your cup once it is brewed. The process is very simple.