The OFL (SIL Open Font License) is more restrictive: if you re-use or borrow anything from an OFL-licensed font, your font must be published under the same license, and you must include the original copyright. But you can still freely use the modified or derived fonts, and you may distribute them. Also, OFL fonts are great for study and analysis. If you’re interested in multi-axis variable font projects, you should check out GG Rafi OFL (figure 3) by Carrois Corporate & Edenspiekermann, GG Scig OFL by Thomas Phinney, Brandon Buerkle and Vassil Kateliev, or GG Club OFL by Eduardo Tunni. And for quick prototyping and experimentation, see the single-stroke (skeleton) fonts GG Stroke Chan OFL (figure 4) and GG Stroke Grot OFL, on which you can experiment with FontLab’s live calligraphic Power Brush.
You can browse and download the collection at fontlab.com getgo — the fonts are available in FontLab’s native VFJ format, so you can open them in FontLab 7. Guides, notes, hints, elements — all the extra info that the creators put in is preserved so that you can get off to a running start.
