> There's software to help with designing these plans, which I guess must use parallel curves under the hood. Siemens PLM / D-Cubed PGM component is one exampl

> There's software to help with designing these plans, which I guess must use parallel curves under the hood. Siemens PLM / D-Cubed PGM component is one example of such software. It's used for the offset function in the sketcher in Siemens PLM own NX/SolidEdge and also in SolidWorks. > PGM automatically generates valid 2D offset profiles on points, lines, circles, ellipses, splines, general parametric curves, and offset curves. > Gaps that arise between adjacent edges in an offset loop are automatically capped using a choice of capping techniques. Offset edges that shrink to zero length/radius, and any intersecting geometry is automatically trimmed, including self-intersecting offsets, offsets ellipses, and splines. https://www.plm.automation.siemens.com/global/en/products/plm-components/pgm.html https://www.plm.automation.siemens.com/global/en/products/pl... Disclaimer worked on the predecessor of that code as D-Cubed from 1995-2000. As a side note, historically, in the Cambridge (UK) school of 3D mechanical CAD, BRep modeling (Parasolid, Acis) the approach to offset (aka parallel) surfaces (and later offset curves with the PGM) has been procedural - thus an offset surface is a pointer to an underlying surface plus a signed offset value. Accordingly, there would be no conversion to Cubic Béziers - all the modelling operations would be made to work with the procedural offset directly. Pretty much all exotic geometry had to be procedural to meet accuracy requirements - that is before the introduction of "Tolerant modeling" in Parasolid around 1992. So, for example, a Rolling ball blend (ie. a constant radius fillet) surface was procedural and had pointers to offset surfaces, which were also procedural. The advantage was accuracy, but the disadvantage was poor performance.