System.setClipboard problem

I’m trying to manipulate the below code somehow so that when you click btn_1 the letter ***A ***is copied onto the clipboard and btn_2 letter B etc. Does anyone know how I could make a bit easier instead of writing out this code to 20-odd times?

this.createTextField("in_txt", this.getNextHighestDepth(), 10, 10, 160, 120);
in_txt.multiline = true;
in_txt.border = true;
in_txt.text = "lorum ipsum...";
this.createTextField("out_txt", this.getNextHighestDepth(), 10, 140, 160, 120);
out_txt.multiline = true;
out_txt.border = true;
out_txt.type = "input";

copy_btn.onRelease = function() {

Any clue how I can do that?