Project not maintained anymore, please use Skin Composer: https://ray3k.wordpress.com/software/skin-composer-for-libgdx/

gdx-skineditor

A skin editor for libgdx 0.3

Easy way to make it run (from console):

git clone https://github.com/cobolfoo/gdx-skineditor.git skineditor
cd skineditor
./gradlew run

You could also use the distribution zip file from DIST folder.