Reversals of every alternate sub-sub-list of a sublist in a list

[magicteddy]

Have a look at this (it works with any cross-section)

Pipe but with Triangle

Hello, You put the start point in the Plane input of the Polygon component, which requires a plane. Grasshopper therefore makes a conversion, and uses XY plane with the origin at the start point, which is why the triangle is flat. You need to use Perp Frame. This component requires a parameter, so you can either use Curve Closest Point to calculate that, or reparameterize your curve and use 0 as the start parameter. [image] Then a Sweep1 works fo define your arch surface. Follow me.gh (15.…