What is the cheapest way to make a burning laser?
Walshy, in short, no you cannot use only batteries to drive a laser diode.
Why do people keep asking that?
If it would work that way, why would we spend money on drivers and make our own complicated ones if it worked without them?
It's there for a reason, you know, not just for sh*ts and giggles.
All information is available here on a silver platter to you. All you gotta do is move mouse a little bit and perhaps type something on keyboard in Search fields.
If you cannot find such most basic information, I'd not trust you with it and hand it to you even more directly, nor would I trust you with powerful lasers.
I once broke a hand too. Didn't stop me from paying a visit to local gaming center and kicking a** like never happened.
Kidding aside,
You can navigate to this forum and type posts. Why would you not be able to search for something on your own?
What part of the arm did you break and how bad?
I won't be taking sides here, Dave has a good point but I don't want to be a douche if Walshy is right.
I'll just make my opinion here:
When you get better, then work on lasers. Now, take some rest, you don't want to add a solder burn to a list of injuries on your hand.
When you can search for information, then you'll be able to use it.