cperko

The WordPress customizer is an amazing tool that developers can use to make their themes easily customizable by their users.
However, creating fields for it requires quite a bit of coding, and lots of trips to the Codex. WPCUI uses a user-friendly design 
to allow the developer to create sections and controls, and get on to what really matters… creating amazing websites!

Customizer UI

Designed to help WordPress developers quickly and easily add Customizer sections and controls.

PluginsPoint

This plugin was developed with CSS and JS with no images or icons. It is pure CSS and the icons can be easily customized by its shape, size and color.
Live Preview: http://kentothemes.com/plugin_demo/
Plugin Features
Change Shape of the icon
Change the color of the shape
Change the size of the shape
Modify the duration of the loader

Kento Lazy Page Loader

Use Kento Lazy Page Loader and beatify your loading icon while your viewer waits for your website to load.

Customizer UI vs Kento Lazy Page Loader