You can use a software for vector drawing (such as Inkscape, Adobe Illustrator or Affinity Designer), create bezier curves and export as SVG file.
Each curve is imported as a path used as input for the inverse kinematics.
You can use this file and draw your curves in the “reachable space”.
You just need to pay attention to the orientation of your software coordinate system that may not follow a convenient convention.
For exemple on Affinity Designer, the X axis is going left to right and the Y axis is going top to bottom, while the Otis model has a Y axis going bottom to top, so we created the flower with a vertical mirror. You can fix that with code once you have found the proper conversion.