How do I thicken a sketch line?
@Anonymous:
You cannot thicken a line directly to a solid. You would either need to sketch a profile to extrude, or you could extrude the line to a surface (in the patch workspace), and then use thicken on this surface. I did this to show you in the attached archive. I first fixed your sketch though, because the curve was not connected at one point).
Not sure if this is what you wanted? The dimensions can of course be adjusted, I just picked some random numbers. Here's a screenshot of it:
Please keep in mind that there are many ways to get to the same result, but this one is the closest to what you asked for. And also, to the question about creating a sketch line just for reference, I'm guessing you ask for how to sketch construction lines. This is done by first sketching the line, then selecting it (left click on it), and pressing 'x' on the keyboard. You can also right click and select "Normal/Construction".