This is just a wallpaper with a blurred empty dock shaped box , This works mainly for dash to dock other than plank, but plank and docky will work too

Settings i recommend to get the best out of this effect
set it as a wallpaper
Go to dash to dock settings and adjust the following and go to position and size
1-Dock size limit : 62%
2-Icon size limit : 48

Now go to Appearance
1-Make sure shrink dash is enabled
2-Make sure customize the dash color is disabled
3-Make sure customize opacity is enabled and input the following:
Opacity: 100%


Thats it!!!
It should look great, You can also adjust the settings to your likings too!!