I would suggest using OpenScad. No need to learn a great deal about it to do what you want.
1) Download and install (free) OpenScad from [
www.openscad.org]
2) Run Openscad.
3) Click in the white window on the left side of the OpenScad GUI and type the following: "linear_extrude(height=0.25)"
3) Drag & drop your DXF file into the white window on the left of the OpenScad Gui. This will result in the line "import("{DXF file path and name}");" being inserted after the line you just entered.
The white window should now look similar to this:
linear_extrude(height=1)
import("C:/Designs/dxf/MyDesign.DXF");
4) Press F6 - you should see the DXF model appear in the top right window.
If the pane goes completely yellow, it is zoomed in too much. You can click in this window and use the mouse wheel or "view" pull-down to zoom in and out, and the mouse buttons to move it.
5) In OpenScad click "File", "Export", "Export as STL" and save the resulting STL somewhere
You then use that STL in Slc3r to create a 3D G-code. The number you typed after the "height=" will determine the thickness of the shape in mm, and if you set it to the same height as the first layer height in Slic3r, the G-code will be a single layer filled-in shape, so you then just need to get your robotic sharpie to understand the G codes, or convert the G-codes to whatever language your sharpie uses. Set the extrusion width in Slicer to the width of the line your sharpie draws to get a complete fill.
Dave
Edited 2 time(s). Last edit at 07/05/2016 08:33AM by dmould.