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 Workhop Effective WebApps without Frameworks is also coming to: MUC Airport.
Airport MUC workshops: Web (SPA, PWAs, Offline, Desktop, Mobile) Applications Essentials and Effective Web Applications. No migrations. #usetheplatform
Podcast: airhacks.fm and newsletter: airhacks.news
A book about rethinking Java EE Patterns