If you are looking for free Dune 3.5 skins, then you can find a whole selection of GUI styles via my website
here - The Intrancersonic Design Source.
Here's just one of the 27+ skins you can find. Abstract contains a skin with many extra files that one can use with other skins provided. The skins included are re-designed in full. (The Browser with the Genetics feature) waveform shaping screen, ect. These, ones listed here are in huge size only. A thread was posted about them here on this forum last year.
viewtopic.php?t=13222#p121005 Preview Image - Smoothe SkinThere are a few that I did which are more like slightly modded/combined versions of the supplied skins for small, large, and huge size. They can be found on KVR's forum.
https://www.kvraudio.com/forum/viewtopic.php?t=573990