Crystal Nodes
Am I allowed to use Crystal Nodes in commercial renders?
Yes.
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.
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 use a curve to spawn the crystals?
Select in your Geometry Node Modifier of your Crystal a (Bezier)Curve as Target Object.