I think I’ve found the solution. On the Trapcode forum I find a post about creating an outline from a text layer. You can apply the 3D Stroke effect. At first nothing happens but by keyframing the start en end position you get the desired effect.
I’ve used your tips and created a text (with the text tool) that is connected at the bottem by a small rectangular. After adding the add shape option and clicking the expand button I copied the shape to AE. After deleting the redundant masks I’m left with one complete mask. So for so good. Now I would like to use this mask as a path for the Trapcode 3D Stroke. But this doesn’t work. I’ve tried to paste the mask into the shape and the position property of the layer. Before I copied the shape I’v put a keyframe at positition 0 to both properties. Am I doing something wrong or am I trying to achieve the impossible ??