How to start a design? Such as a cup.
A function- what is it for?
To hold liquid, something flowy.
How could such matters be held in a container?
Should it be shallow, should it deep?
How you want to use the cup? What is the best feeling about a cup?
To hold something warm for that freezing fingers, perhaps on a cold rainy day.
What is the best way to warm the hands?
Perhaps to have them surrounding the cup.
If so, what is the best shape?
Following the curve of hands, I would presumed.
Then the form emerged - deep enough to hold a good 250ml, big enough for both palms to wrap the cup, curved to provoke a comfortable feeling when you wrap your palms around it.
But, is this enough?
What about the material? Metal and glass could be to hot to hold, wood and ceramic or rock could be great. Weight wise, perhaps we could eliminate rock, wood types, sustainability, varnish could be further studied, ceramic could be a good choice, as it is easy to mould, with a understatement shine, elegant and felt warm.
So ceramic it is.
Then how thick? Strength, curve, thermal mass affect the design too...I would go for a design slightly thicker at the bottom, come to a taper at the mouth, beveled and thin rim allow a better flow of liquid and more friendly to the soft lips.
I then considering the effect of the cup under the light, if I would like a polished look then a good smooth surface; or perhaps some texture to enhance the grib and with casted shadow, being out the 3d but it could be more cottage feel. Playing with light and shadow to decide this last detailing should be fun.
Lastly I could sit back and choose the best colour for the cup, perhaps a rainbow series.
To Me, design is the final product of One self-searching process. It is about throwing Oneself with questions, and answer them honestly and professionally.