Fibre filled resin or PE cards can be sharpened and used for cutting but they neither get as sharp as metal nor do they hold an edge well. Flint can get reasonably sharp and hold an edge but itīs tricky to make. There are also ceramic blades which can be used.
Bear in mind that most alternatives are known to security personel. They will possibly presume that you wanted to conceal a weapon when they find it. This could easily mean more trouble than a metal blade.
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If it isnīt broken, it doesnīt have enough features yet.