Crystal Nodes
Why do all the crystals change the scale, when scaling the radius?
Try to decrease the scatter distance in the Geometry Node Modifier of your Crystals.
Where can I scale single areas of the curve-crystals?
Select any point(s) of your Curve in Edit Mode and scale the radius.
You can find the exact value in the "n-panel" ("n") > main radius.
How can I draw a curve to add Crystals on a Mesh?
In your Geometry Node Modifier of your Crystal:
Set the Mesh on which the Crystals should appear as Attracting Mesh.
Set a (Bezier)Curve as Target Object.
In Edit Mode of the BezierCurve:
Select the draw tool (in the left panel > "t") and draw on the mesh.
How can I use a curve to spawn the crystals?
Select in your Geometry Node Modifier of your Crystal a (Bezier)Curve as Target Object.
Am I allowed to use Crystal Nodes in commercial renders?
Yes.