Hey there,
first of all I want to say thank you to all of you for your suggestions and advices. I managed to solve my problem with the DynaShape Package as I found out how to drag the handle points only in z-axis
As this fits better to my other topic, where I am looking for a Package that allows to drag points in only z-axis, I will upload a video this evening there where I show you what I came up with.
Nevertheless I am still really interested in your approach on presetting a number slider via a view extension!