Our online quoting system now allows you to add engraving to your parts when using a DXF file. Just create a new layer called "Engraving" and add all of the things to be engraved to that layer. Note that we don't yet support the HATCH (filled area) or TEXT entities in DXF files.
For example, in QCad, just click the "+" button in the layers list to add a new layer:
You will be prompted to enter the name of the new layer. Enter "Engraving" (without the quotes). Your layer list will now look like this:
Finally, add any lines, arcs, etc. to be engraved to the Engraving layer by setting their Layer attribute (Modify -> Attributes -> Layer:).
Upload your DXF file now to try it out.