Scribed lines for welding indication

Hi all, to fasten the welding process of my boats, id like to add lines that the cnc machine can scribe so the welder knows where to locate parts.

In solid works this is done by marking a very shallow cut. If i do this in rhino, the polysurface (that needs to be closed for the cnc software to recoqnize it) is opened.

Of course i can close it all up again, but there are mant scribed lines to be made so i assume there should be a beter way…?

Many thanks,

Hey Huib -

It sounds like you could use a box (or piped curve) and Boolean substract that from the object?

Like this?