This page contains some handy tools for working with OpenRocket design files.
OpenRocket is a sophisticated, freely available, rocket design and simulation program widely used by rocketeers of all levels.
Get back a .dxf file of one of your trapezoidal or free-form fins generated directly from an OpenRocket file. Now you don't have to re-draw your fins from scratch to get them cut out on OCL!
Fin Extractor Workflow Tutorial
Here's a YouTube video showing how to use the Fin Extractor to create a .dxf for your fin and then importing on to a blank drawing template using LibreCAD.