Original by SSRATT: [link]
Edit by calvis101: [link]
I optimised it for my machine, so it may not work for you at first. You'll most probably have to modify the files yourself.
Basic knowledge of Rainmeter code is required, but nothing fancy. Have fun.
Updated to use buttons for Media Control. They come in two variants, one of which uses a fade effect which can be quite buggy, as in it may make the buttons disappear when skin is refreshed while no music is playing. Second variant is more stable but doesn't use fade effect, instead switching to reduced alpha instantly when no music is playing.
How I did it, was I took a regular icon, used GIMPS color tools to change colorisation to match the default "folder" icon (or grabbed the color straight from it and recolored the icon manually), then duplicated the layer, put the copy on bottom and add blur to it.
Here's a crappy image tutorial: i.imgur.com/w0yNnsO.jpg
As for your other comment, I already posted it to Reddit when I created the skin, but if you don't think people will mind, feel free to post it whenever you want, just don't claim it's yours, as always.