Hi Alex, the regular Construct > Sweep command can already be used for that. Draw your custom shape off to the side outside of the bounding box around the curves (to initiate "auto place" mode for the sweep as described in the video tutorials here: http://moi3d.com/3.0/docs/tutorials.htm) , then select it and run Construct > Sweep. Then when it asks you to select rails select all your wireframe curves. That will then do a one-rail sweep with your profile on each rail curve, making a custom profiled tube over your curves.

Basically the Sweep command is the regular way of making tubular shapes, and takes a profile curve that you have drawn so it can be any shape you want. The Pipe command is a simplification of Sweep that just uses a circle for the profile shape with the circle being automatically created for you. So if you want the customized profile version just use the regular Sweep command.

Here's an example:





- Michael