Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:4178313.
This is how I made the artwork cube for thing:4176562. The basic workflow is as follows, including workarounds for various limitations of the tools:
To prepare the dxf files, bitmap images were taken from artist064. I played around with several variations, adding borders, negative image, scaling and blurring before finally converting to two colour using Threshold filter in GIMP. In the end I settled on a sharp black and white variant without border or blurring.
Then using "Trace Bitmap" function of InkScape, the files are converted to a vector. Some minor touch-up was performed to prevent non-manifold geometry (eg. where two corners touch), I also experimented with various path simplification settings but found this was unnecessary. The curves were flattened using the "Flatten Beziers" extension ready for export as dxf, paying attention to format options, scaling and units. (There's a few good tutorials on this subject).
Due to OpenSCAD crashing when trying to combine multiple imported dxf files into a single model, I emboss each face individually onto the face of a cube using import and linear_extrude. I have elongated the cube to make deleting the extra faces easier. The resulting stl files are all loaded into MeshLab where the extra flat faces are selected and deleted, leaving only the embossed face for each mesh. Then combine with "Flatten Visible Layers" and export the final mesh.