Here you will find everything needed to remake an actual zoobka. You will be able to examine the settings used at each step and therefore learn precisely how I proceed. Time needed to complete the step-by-step: less than 10 minutes
Click the button "Clone or Download", then click "Download ZIP". Unzip and follow the instructions in Readme.txt
The Zoobka tutorial: https://www.gimp-forum.net/Thread-Zoobka-A-technique-to-make-beautiful-material-effects
Some samples of zoobkas: https://www.deviantart.com/g017/journal/New-Zoobka-Art-Beautiful-abstracts-in-no-time-829163839