Looking for the best t-shirt mockups and PSD templates for your online store? Over 100+ High quality Premium PSD Mockup. Whether you’re designing your own t-shirt or looking to add higher quality product pictures to your store, you’re sure to find the perfect t-shirt mockup in here. A t-shirt mockup is essentially a blank t-shirt that you can add your product design on. they may just feature the t-shirt on a plain background. PSD is the name of the Photoshop file kind of like the .jpg extension for images.