Detail this asset from Unity Store: Original Link
This is a paid asset, but now you can download EGUI Free.
EGUI v1.3.0 (Latest version)
Egui is a builder of Game UI that will help you create professional user interfaces very quickly and easily, regardless of whether you are an indie developer, student, freelancer or game studio.
This library contains such elements as buttons, windows, and other various elements (coins, energy, and so on) necessary to create game ui.The peculiarity of this library is that the color scheme of the elements is completely changeable. You no longer need to constantly go into graphics programs (photoshop, gimp, and so on) to change the color of the elements. Due to this, the creation of the game is accelerated at times, since you have to spend much less time on the gui.
* This pack will be constantly improved and supplemented with new elements *
-300+ elements (Buttons,Windows and other elements)
* Fully customizable color scheme *