I have a variable pitch helix. It's possible I could have many stages all of different widths.

what I'd like to do is sweep a horizontal line piercing the helix around the helix but the width of the line as it sweeps around should change so it is as wide as the pitch at that point. Effectively I want to get the two extra helixes that are  half a pitch to the left and half a pitch to the right of the point on the current helix and use them as guide curves. Note in this case I've shown constant diameter but I may want to change the diameter at certain points along the helix as well.

Can anybody suggest a clever way to do this?

Brad