You can get my designs on three stores.
First is Zazzle, which has a selection of T-shirts, mugs, and pretty much any other item you can print stuff on. You can find my shop here.
And the second one is Satoshistore.io, which is a bitcoin store with t-shirt apparel. You can pay with lightning there and Janine will take good care of you with quality threads.
The third is Plebtag. You can get boltcards with LEDs that light up when you use them, here are my designs. https://plebtag.com/shop/artistcards/georgesaoulidis/