Chat API

I was wondering if you could write an API or a mod which can write messages to the In-game chat, for example in my technic world, I have a diamond factory, and it would be nice if it would inform me when a new Diamond was created…

Well, there's a peripheral that let's you send chat messages (and some other things). I think it's called Op Panel or something like that, and you need to be an op to use it (or play in single player).

So where can i get it and how do i use it?

Here's the post on the peripherals forum. The instructions are there.

thanks!