There's one made by this site, but I don't really like it because it only lets you do whole pounds, not decimals. Like, it would do 140 but not 140.6 or anything.
Ticker factory has one that can do decimals, and I prefer that. Here's the like if you're interested.
It'll have you make a PIN number so you can go back and change your ticker anytime. It's easy to get to - you can go back to the site manually or just click on the ticker once it's in your signature and it'll take you there.