Here I have released the version 1.5 of Geonkick percussion synthesizer that now is based on Redkite GUI toolkit I have developed. It is free software released under GPLv3.
Version 1.5 includes the following new features:
multi-layers (3 layers)
oscillators phase modification
using Redkite GUI toolkit instead of Qt, thus, enabling proper LV2 support
non-blocking audio thread, using atomic operations and kind of ring buffers
on modifying parameters no glitches
non blocking GUI when using long kicks, times like 4 seconds
Source code: https://github.com/quamplex/geonkick/
Here also a quick track I composed the last two days using Geonkick for percussion: https://soundcloud.com/geontime/building-a-new-world
Now I'll start the next cycle to continue the development of VST3/Windows, maybe after a month or two to release VST3.
Hope you'll find it useful... and hope it works for you.