That sounds cool. I try to improve my graphic design skills. I only started working with design software a few months ago and I can say that it isn't as easy as it sounds. I was recently looking for art for my design and needed to find a realistic image of an iPhone. I found free mockups of different iPhones on this site https://www.ls.graphics/free-mockups/free-iphone-mockup . It seems to me that such ready-made free mockups are very helpful for budding designers and this is a really good job. I hope that soon I will get better at this and be able to create my designs for t-shirts.