I would like to extrude naked or unwelded mesh edges in Grasshopper.
There’s a Rhino command and I see a MeshExtruder Class in RhinoCommon but this is beyond my skills.
How is this done?
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See attached
Mesh_Extrude_V1.gh (127.4 KB)
BTW: A naked edge is the one that has one adjacent Face (see inside C#). Pay attention to the mapping (Normals indexing is not the TopologyVertices indexing).
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Thank you, that looks promising 
5 minutes job … so indeed has some(?) future (?).
Get the next version (Lists added, some checks added - but in general avoid non Manifold meshes and/or bananas meshes). In any case ALWAYS combine IdenticalVertices prior the EF connectivity part (and reject the resulting Mesh if becomes invalid - for any reason). Have in mind that Vertices are on a per MeshFace basis while TopologyVertices are on a per Mesh basis (see inside C#). That’s the reason that this Method returns (potentially) an Array:
Mesh_Extrude_V1A.gh (119.5 KB)
BTW: In real-life (general case) you’ll need an approach for self-ccx events (Kinda the R Method that yields self ccx events on a Curve - see SDK) … so if this IS for real-life I could add some lines more on that matter (i.e. do NOT accept a non rational - amplitude related - result blah, blah )
Say:
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