I don’t know exactly how hard it is to make a martial art from scratch, but I’ll probably fiddle with the idea soon(as my first mod, maybe), because it’s just something that I feel it’s missing. Many melee weapons doesn’t have a MA that fits them, and IMO they add some spice to the combat by adding all them special moves and stuff.
Also, why anybody hasn’t fiddled with the idea of making a Fist of the North Star MA?
I mean, seriously. It’s an awesome concept, even if it’s not going to be balanced.

I made a few martial arts based on the Chinese weapons (staff, jian, qiang, dao) that are good-to-overpowered (the intent being to make those weapons competitive with fencing/niten). It’s not that hard unless you’re trying to do something that existing techniques don’t do, rather than mixing and matching existing effects.

Yeah, that’s something I have in mind but I did think that it would be harder to make new techniques than to use already-made techniques. Do you know where I should start on making the techniques themselves?

Making new techniques isn’t particularly hard - you can look at techniques.json and define your own (and assign them to your own martial art) relatively easily. However, they all pull from the same general library of effects - damage/dodge/attack speed buffs, a few set areas of affect, stun/knockdown/knockback, etc. . So combining a few of those (say, an attack that did half damage and gave you a stackable buff to attack speed and a stackable penalty to block, to represent a flurry of attacks at the expense of defense) is easy, but creating an entirely new effect (say, an attack that inflicted heavy bleeding and gave you an “enemy’s still-beating heart” item) would be difficult, or maybe impossible.

pretty true
spent something like 3h (maybe less) making this thing
[ { "type" : "technique", "id" : "tec_sojutsu_deflect", "name" : "Spe - - techniques.json
martialarts.json - - martialarts.json

It was a pretty fun process. The techniques I got from various videos and websites, but primarily this video right here:
Now I need to make some martial arts book and MAYBE set it to be avaiable with the Melee Weapons Training trait. Also balance it, cause I feel it isn’t really much balanced. The overhead “strong” strike for example only does ~10 damage with qiang, but I’m pretty sure it would do a hella lot more damage on a cutting pole weapon like a Naginata, but I haven’t really tested that.
Also fine-tune it so it can be more like the real thing.

EDIT: So yeah I completed it by adding it to itemlists on dojo, and now you can get it from the melee-weapons training trait.