This isn't fully my design. I used the online software named Kittl to design this awesome illustration. This is a template which was on their website. And I just add the words "Dad" and "fuel" onto the already designed illustration. You can find this design on my online store for as said Tee Shirts and Mugs. Well, on other items too. And you can find many more like this on their website.

Dad Fuel Graphic Tee Shirt and Mug Design