3GB isn’t that much these days. Grab a 3TB hard drive. Fill it up with harmless content. Hide 0.1% of information in amongst the almost 3TB of photos of kittens. You can never have too many photos of kittens, right? 
It is a bit unwieldy.
The obvious direct answer is: store it on an external drive. That answer has already been given.
Another answer is: store it on the internet.
Have a bit of fun with it. Store it distributed on the internet. I believe there are already schemes for that kind of thing but I am not across the details.
That’s in addition to the previous post, which probably has the real answer.