A Minecraft random item crate plugin?

I need a Minecraft crate plugin, where there's a kind of crate from which random rewards can come out. It is important that it sets the probability and that I can insert my own items there. Does anyone have a suggestion or anything like that? (Version 1.12.2)

https://minecraft-de.gamepedia.com/...tetabellen

Golden crates

Well, that's pretty good on the whole, but that's supposed to be a kind of jackpot system, but you can't look into the box

You mean the item should only be dropped? Maybe just spawn an invisible entity / mob and kill immediately.

Search in your world for sometime in the world a chest was with me on the surface