Then all you have to do is adding elements and/or panels according to what you need and to the way you want to organize your skin. First thing is to erase whatever element is here by default (NG Playlist normally) and to insert an horizontal or vertical splitter as a base, or a PSS (right click/insert). Otherwise, you can decide to use Photoshop or Gimp or any other program to create images that you'll assemble using Panel Stack Splitter.

If you're good at coding and you're not too ambitious, you can stick with foobar2000's code to create graphic elements.

Just copy the core files (database etc.) from an installation to the other to keep your library and media player settings.

I mostly use portable installation instead of normal installation, for it's easier to install skins into and you can multiply your foobar2000s as much as you need, knowing that there will be no conflict of any sort (no need to update anything or to have two skins aside).

Beware the updating of components, which can disable a part of or the entire skin however it doesn't happen a lot 'cause AFAIK no component is currently under development.

That being said, if you've checked the components and their version and there's no conflict, you sure can install several skins on a single foobar2000.

I personnally recommend to install skins in fresh foobar2000 installations to avoid compatibility issues between different versions of a component (WSH Panel Mod in particular).

Backup your files if you're not sure of what you're doing export or copy your working scripts when you're about to take risks.

Avoid installing old skins on current foobar versions and vice versa.

When installing a skin, check the version of foobar it's been designed for.

Always keep your components up-to-date, unless it may cause compatibility issues.

How to install foobar2000 skins