A weird experience with this one. For a long time, Printful (the manufacturer of this shirt) wouldn't recognize the PNG of this design as a valid file. I tried everything I could think of - resized it, copied it to a new image, flattened it into a JPG and then remade it as a PNG, renamed it, stripped all the meta data off. No dice. Then I uploaded a different PNG to make sure that the site wasn't just having a general transparent PNG problem, but that uploaded fine. Then I uploaded a JPG version of the Satan design, and that worked, too.
In the end, I went back to the original GMP file (like a Photoshop PSD file, but for GIMP), and copied out individual layers to a new image, then saved that as a PNG after the thing was rebuilt, and submitted it successfully. Weird!
At any rate, here it is, and I have to say that this one of my favourites so far. The main image was provided by Midjourney, of course, but a lot of work went into the finished product. I'm particularly happy with the desk he's working on; another example of my efforts to work outside the rectangle.
Manufactured by Printful.
Have a look at this t-shirt's spec sheet here:
https://www.printful.com/custom/mens/t-shirts/mens-classic-tee-gildan-5000
"The 100% cotton men's classic tee will help you land a more structured look. It sits nicely, maintains sharp lines around the edges, and goes perfectly with layered streetwear outfits. Plus, it's extra trendy now!
• 100% cotton
• Sport Grey is 90% cotton, 10% polyester
• Ash Grey is 99% cotton, 1% polyester
• Heather colors are 50% cotton, 50% polyester
• Fabric weight: 5.0–5.3 oz/yd² (170-180 g/m²)
• Open-end yarn
• Tubular fabric
• Taped neck and shoulders
• Double seam at sleeves and bottom hem
• Blank product sourced from Honduras, Nicaragua, Haiti, Dominican Republic, Bangladesh, Mexico
This product is made especially for you as soon as you place an order, which is why it takes us a bit longer to deliver it to you. Making products on demand instead of in bulk helps reduce overproduction, so thank you for making thoughtful purchasing decisions!"