an external graphic card



Short answer: Doesn't exist on the market just yet, but if you have the time and parts, you can build it.

Edit: Andrea beat me to it lol

Long answer: In terms of something going to a store to buy or a DIY kit? Currently, I'm pretty sure there aren't any products out there that is just a plug-and-play. Additionally, how old is the laptop? You will need a fast enough and compatible connection between an external GPU and the laptop. (Thunderbolt and USB 3)