Create and modify 3D models > Create 2D geometry > Creating valid profiles
  
Creating valid profiles
Sometimes you will receive an error message that says your profile is not valid, even if the profile looks fine to you. For example, this rectangle looks closed:
However, when we tried to pull it, Creo Elements/Direct Modeling found a 1 mmgap:
The problem area is identified by yellow marks in the viewport. If you zoom in, you can see it clearly:
Common profile mistakes
Breaks
This problem was illustrated above. To solve it, draw a line segment to close the gap.
Intersections
When lines intersect, the point where they meet is infinitely small and is not manufacturable. To solve this problem, separate the two entities so they can be machined separately. After you machine the 3D solids, you can move the two parts so they touch at their corners.
Branches
Branches are similar to intersections. The extra line shown in the middle of this rectangle could extend to the other side, as shown here, or might end inside or outside of the rectangle. Parts like this cannot be manufactured. To solve this problem, you must delete the extra elements or move elements so they form separate profiles.
Overlaps
You won't see overlaps until you try to machine a profile. To fix the problem, use the Merge command in the Modify 2D menu and draw a box to select the problem area. This will merge the lines so you only have one profile, rather that two stacked on top of each other.
Tangency
Like intersections, tangencies cannot be manufactured in the real world. You will have to remove the tangency to solve this problem.