Thingiverse‘s Customizer allows users to customize suitable OpenSCAD models without knowing any OpenSCAD code. While it does have some documentation to help developers along, there’s still a lot of guesswork.

I released my first (working!) Customizer design the other week: Parametric Finger Pen Holder (Vertical). While the docs are the primary source of developer information, you might want to know the following:

• Customizer assumes that every variable defined before the first module definition in the script is a user parameter. To give it a hint that it should stop displaying variables, add an empty module (such as module naff() { }) after the last variable definition you want Customizer to display.
  (There’s supposed to be a CUSTOMIZER VARIABLES/CUSTOMIZER VARIABLES END comment pair that will do this too, but it didn’t work for me)
• Customizer will fail if there’s any character other than strict ASCII in the script, and won’t give useful diagnostics about the problem. Check your comments for accents and fancy punctuation
• Customizer displays a real-time preview of your model. This means the rendering will be a little rough, especially if you use set operations such as union(), difference() and intersection(). If you have to hit F6 to render your model in OpenSCAD properly, it’s going to look a bit off in Customizer
• If you must use resource-intensive functions such as hull() and minkowski(), try to limit them to 2D paths that are subsequently extruded. Everyone else in the Customizer job queue will thank you
• Similarly, keep the circle smoothness variables ($fa, $fn, $fs) in sensible ranges
• Customizer creates a new Thing under your name rather than just letting you download your customized model. You likely want to delete that once you’re finished with it.
  (This also means that Customizer only works for registered Thingiverse users. I can’t see any way around this, unfortunately)