So, what I did was, select a plane that is normal to the end face of this sheet metal part, then, use the spline line to create a curve which is exactly snap to the mid point of every step faces, base on the spline curve, extrude a surface which will pass through the sheet metal part. Finally, use the intersection curve to obtain the line that exactly fall onto every bend surfaces.
I have received an imported sheet metal part and was asked to create some cutting along the stepped faces. Normally, when we plan to create some cutting along a folded part we will rather to make it flatten so that it is easier for us to sketch out the shape on the flatten face and proceed the cutting. For this imported part, the difficulties I face here is, I can’t flatten it since the imported sheet metal part have some broken surface and that need quite some time to repair before we proceed to flatten it.
Here’s the video which shown you more clearly about what I have done!