Lin3s is a simple CAD web tool that enables you to create 3d objects from simle line drawings. It works great for paste extrusion and air pressure extruders. Lin3s is developed by 3digitalscooks crew and they use it in their 3d printed food projects. Great work!
Here is a basic tutorial on how to use Lin3s with main options:
... and here is the result 3d printed with hummus (yes, hummus!) mmmm on nom nom ...
You can use it via web interface here: http://www.3digitalcooks.com/design-tools/lin3s/lin3s.html
...or learn more about it here:
Interface is very simple: