Default I am thinking to make an app with multiple clock widgets

Hi, i have searched the forum but i didn't find exactly what i wanted.
I have on my mind a small app with 1-2 activities which will be able to change the provided widget, not something extreme, only a few already designed clock widgets.
It's memory usage to have 3-4 installed widget and takes more space in widget list, and it's more cool an app like this
I checked sources from Google apps but it was too complicated for re-use (ads, payment options, server data etc..)

Can you help me plz, with an example or something familiar?
Thanks

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