One thing that makes bullet patterns are the bullets themselves. (Also, people die when they are killed.)
So what about a topic where you can upload the bullets you made?
But an armory wouldn't be good enough if it only sold arms and ammunition. An armory is also where you can receive advice and discuss ideas about whatever leaves your familiars, index finger, artificial sun, and core. So let's use this topic not only for the trading of bullets, but also for the trading of ideas.
What would you think of as a good projectile for danmaku games aside from the standard Touhou bullets?
Some games have meteors as attacks, which I think would be totally okay if it was used as projectile in danmakufu. But what about ninja weapons, like shuriken? Or cherry petals? Beer bottles? Babies? (Okay, scrap those two)
Do you have any more ideas? Or do you have bullets of your own for trade?
Edit:
Okay, here's a few samples of what I whipped together at work today:
Ninja weapons! Touhou doesn't have a ninja character (I think), so these can make you more original.
They are magnified by 200% from the original size so you can actually see them. Once I get more graphics I'll make a template for it.