You can download the Mix Lab 3.1 skin directly from the official VirtualDJ Extensions
Enhanced Mixing Tools: Includes advanced EQ crossfaders and refined visual joggers, designed to make transitions and scratching more intuitive. virtual dj mix lab 31 skin download new
Resolution: The skin is natively 1280 x 800. While VirtualDJ 8 can resize skins, it may not look perfectly sharp on high-resolution widescreen monitors. You can download the Mix Lab 3