This model was based on pg.75 of a wallpaper sample book on the Brooklyn Museum website. The wallpaper was originally made sometime between 1875 and 1917 by Morris & Co. Ltd.

https://www.brooklynmuseum.org/opencollection/objects/97900

I took the image and edited the image in GIMP. The goal of editing the image in GIMP is to adjust the brightness/contrast so that the later trace bitmap feature in Inkscape only captures the detail desired (there may be lots of low-contrast details that won't translate to a printed object well). You can either directly use the brightness/contrast adjustment (easy but limited) or use the Colors -> Levels menu item (more difficult, but more control). Then export the new high-contrast image to .jpg or .png.

Take the resulting high-contrast image and import it into Inkscape and then trace it using the 'Trace Bitmap' function in Inkscape and more specifically the 'brightness cutoff' method. Play around with the smoothing and optimization features in the second tab to get the cleanest result. Then I manually edited the trace to remove all "extraneous" isolated islands (such as dots that don't add much to the overall design). Then I connected all the remaining shapes to each other to ensure that there is connectivity between all pieces and the frame. These last two steps are accomplished using the path edit tools inside Inkscape and the join tool in the path edit section.

Export the resulting trace SVG from Inkscape and use OpenSCAD to extrude the 2D SVG into a 3D shape (see included .scad file here on thingiverse). You can add a frame either inside OpenSCAD or in the prior Inkscape step.

I have also provided the OpenSCAD source code and Inkscape file. I used OpenSCAD version 2018.09.05 (git 40af343) to render this STL.

It would be really cool to see this made using a laser cutter, paper cutter, or CNC so check out the SVG file if you want to make it that way. If you like this design then check out my other "Art Nouveau Silhouette" design with a similar style:

https://www.thingiverse.com/thing:3180640