How much time would it need, when these cups would be filled with different
juices?

Le'mme see:  subsurface scattering with scattering media... hmmm, about 3 months? ;)

> The final result isn't a waste of time!!

thanks.  you're very kind, but it really is:  the shadows are too sharp and there are no caustics
to feel realistic.
And no, I'm not trying those... :P