You can buy new bottle cutters online (here's a good roundup of options) but their ability to cut different sizes, angles, and bottle shapes are severely limited.
Of course, there are loads of potential projects to be had, so instead of buying a bottle cutting jig, let's make one!
Bottle cutters were everywhere in the 1970s...tucked in with the macrame and string art kits, they allowed hands-on folks to create recycled vases from wine bottles, or drinking glasses from jars, cool lamps and lighting fixtures, and all kinds of upcycled goodness, like this great project by my friend Tyler Goodro:
Unfortunately, the kits are increasingly rare and growing more expensive on eBay, so it's a pretty big investment if you're just interested in learning and not planning on cranking projects out in bulk.
A few weeks ago, the ManMade community rejoiced over the release of the Ninjabread Men cookie cutters from Fred Flare, which are still not available for purchase. So, industrious James Williamson, an electronics engineer living in Lancashire, UK, created his own, and is sharing his template with the world!
James' versions hinge around a acrylic template (he'll laser cut it for you for cost!), but you could easily print yours out onto paper.