Well, I really don’t understand why you should design your own T-shirts? Now the choice is so huge that if you search you can find absolutely anything. For example, have you ever seen hentai tees in retail? But I've seen ... To be honest, it was even a little scary. I would like to see a girl in such a T-shirt. Lately, I've been trying to be discreet in my choice of clothes. I really like military style clothes. I usually buy it from
https://lionlegion.co.uk/. Yes, this is not exactly what you expected. There is no anime stuff, hentai, yaoi and other nonsense. Just T-shirts with a cool print. Some might even like it.