# Geometry Nodes: extrapolate faces, but beginning at a random initial offset distance

I'm generating a load of noisey lines from a subdivided icosphere that extend to a certain length. However, I want them to begin extruding above the surface of that icosphere, aka I would like there to be a gap between the icosphere surface and the beginning of the extrusion line. This gap is to obey a [noise] node, preferably,

Rohan calls for aid.

Update This is a section description of what I'm after

ps. I'm a blender noob. Small words and pictures plz.

• You could separate the faces, move them along the normal, and then extrude them. Apr 16, 2023 at 0:53
• Please do not change your question after an answer has been given. Open a new question instead! Apr 16, 2023 at 10:29

To solve this task, you could use the value you use to extrude as a selection with which you first separate the desired faces.

Then you can move these faces according to their normals and extrude them.

The normals of a face always have the length $$1$$ and by scaling these normals and using the values of the node Random Value as factor, you create the offset for the faces.

You then just need to extrude them accordingly and join the previously separated faces to the extruded mesh to create closed objects.

Here would be the basic approach:

Since you have now changed your original question three times, I hope that you have found your solution with it.

(Blender 3.2+)

• Thats fantastic! Thanks! However (I've attached ehre my file so you can see how it differs) drive.google.com/file/d/1D3spNiRpWCb1u5gOwnQ1kOR_38Z4n9-e/… - the random value attached to the scale only served to shift the trajectory of the extruded lines, not variate their forming altitude. - Also, given my complete novelty at nodes, would you mind showing me how I could close the faces on the inner faces? Apr 16, 2023 at 13:13
• @TheCodingKarp To close the extruded mesh you can use the following setup: i.sstatic.net/nwJ09.png Apr 16, 2023 at 13:45
• Cheers @quellenform! Any ideas for shifting the origin altitudes? ps. could I ask, what are the best resources you used for getting your head around the nodes available, back when you were learning this stuff? Apr 16, 2023 at 14:33
• @TheCodingKarp I don't understand the question now. Do you want to move the faces randomly along the normal and extrude with constant values? One of the best resources is blender.stackexchange.com. This is where I started learning Geometry Nodes a year ago by looking at the questions and how to solve them. Apr 16, 2023 at 14:58
• @TheCodingKarp I'm sorry to say this, but you already had the right answer in front of you. I hope this update will lead you to your goal. Apr 16, 2023 at 18:12