Yes, it should be fine to use the visualizer, just know that credit for that goes to bikibird.
And the best current video tutorial for custom instruments that I know of is this one by Gruber.
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Used this in a Jam game! https://thefogdemon.itch.io/slimescale
Credited it in the description and when I update it and have time to add a proper ending I'll add credits there too.