Trying to isolate surface within block so the entire surface matches

[snoofydog]

Hello

I'm currently needing to make a mould for a part using the topography of a surface (shown in red).

Due to the nature of the material being moulded, I cannot have walls on the mould. So the surface just needs to undulate.

I've tried extending the edges (in Patch) but find this adjusts the surface topography. Only other option I've come up with is offseting the surface, then thickening and then use that as a cutting tool - this leaves a wall around the part.

Can anyone offer any other solutions?

[etfrench]

Where's the red? 

[lichtzeichenanlage]

@etfrench: Have you enabled Inspect -> Component Color Cycling  Toggle (Shift + N) ?

[TrippyLighting · Accepted solution]

I would have suggested extending the surfaces as hat sound like you might want.

I had not problems doing so and I don't see how it adjusted the surface.

Did you try any of the options in the extend surface dialogue :

[snoofydog]

Thanks so much, I didn't select the tangent edge.