The normal to surface constraint is an addon in python for Blender that calculates the normal vector to a mesh and applies it to the object. Strangely, this is one of the constraint that doesn't exist and that I missed in Blender.
You can find it here : https://github.com/StanPaillereau/Blender_Addons
https://m1.behance.net/rendition/modules/140474233/hd/166291c76690fdbc04587dee2c0ae642.png
The addon creates 2 buttons in the "tool panel" > "Relations" > "Create Normal To Surface constraint" to add/remove the constraint :
https://m1.behance.net/rendition/modules/140473411/disp/1b45c2a7b183ea1efe6b838fc9c7d66d.png
Once the constraint is added to an object, a set of buttons appears in the UI panel ( > "Custom Constraints"). They allow you to change targets/normal axis/up axis, enable/disable or delete the constraint :
https://m1.behance.net/rendition/modules/140473413/hd/66b9549ce149f2f64f6dec9f50e99f01.png
