That may be pointless depending on your printing device(s). Even setting something's lineweight to zero, which will use one pixel on-screen and the thinnest line the printing device is capable of, will likely be more than a fortieth of a millimeter.
But if it does have meaning, though it doesn't seem you can do it in drawing, you can for printing, in the Edit Lineweights... list in the Plot Style Table Editor. I think the number of them may be fixed -- pick one you would probably never use [such as the fattest one], pick the Edit Lineweight button, and change it to 0.025. Then assign that lineweight to whatever color(s) you choose.
@f.annoscia1XRNMD wrote:
Could you explain to me. For the polyline can I give a thickness at will?
Careful.... "Thickness" in AutoCAD is up off the page in the Z direction. You can give a Polyline any width you want, but that's in drawing units. If you're plotting at full size, that could work for you, subject to the printing device resolution issue I mentioned before. But it's not the same as displayed Lineweight that's controlled by the Show/Hide Lineweight toggle, if you want that the same regardless of Zoom level or plotting scale.
Not to mention the fact that there will inevitably be things you want to give that Lineweight to that can't be drawn as Polylines.
