Info on Open Path Font (.opf) format

There have been several threads over the years regarding how to generate true open path or single line fonts for use with plotters, cnc machines etc, as well as the related font formats. I do not have the expertise to solve this problem myself, but I do want to provide the info I have collected on .OPF format fonts which are currently used with 3 consumer level desktop cnc design/driver programs. It appears that OPFs are simply intentionally broken TTF/OTF fonts given the new extension. I am providing this information in hopes that someone who shares this need can possibly take advantage of it to kick this can a little further down the road.

software that can use .opf fonts:
Make the Cut
Pazzles InVue

sources for .opf fonts:

links and videos referencing (andy is the developer) (01:47:50) (1:16:43 focus 1:32) covers how to create opf fonts


As I recall, that is basically the case for the OPF files, that they’re simply TTF files with glyphs that all have open paths. You might be able to produce them by exporting as TTF (making sure Remove Overlap is unchecked) and renaming the resultant .ttf file to have the .opf extension. To export as TTF, select the OTF icon of File > Export… (Command-E) and then select the Save as TTF checkbox.

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Thanks for your input, composerjk. I am using Glyphs Mini and I don’t have a Save as TTF option, unfortunately. I did try renaming the OTF font and it did not work (font loaded into SureCutsALot4 and Make the Cut fine, but a closing segment had been added to each open path). Seem to recall trying the ttf route with a trial version at one time to no avail, but would love to confirm one way or the other whether this works in the current versions of Glyphs.
I should add that according to the developer of Make the Cut, either OTF or TTF should work when changed to the OPF extension.
edited to clarify and add new data