Substance is a free (BSD) look and feel and comes with many skins and configuration options.
It is easy to install and configure. I used substance even for NetBeans in the past.
NEW online workshop: Web Components training (online)
Airport MUC workshops: Java EE 8, Java 9: Bootstrap, Effective, Architectures, Single Page Apps, Progressive Web Apps, HTML 5, ES 6, CSS 3 and Microservices
Podcast: airhacks.fm and newsletter: airhacks.news
A book about rethinking Java EE Patterns