The product is this: https://www.redbubble.com/i/t-shirt/Instinct-vs-Ego-by-Geekdom101/142269246.IJ6L0
I think they did it on the server but I am perplexed on how they were able to do it. I have not found any tutorial online that satisfy this kind of requirement. Might be threejs but what are the steps in doing this. Thank you
It can be done in threejs and it will be much cooler because the customers will be able to orbit around the models
decals. a decal projects an image onto any geometry.
if you click canvas.js that’s all there is to it, the rest is just the UI and state model.
anderson mancini and i made a full course about it in case it interests you https://www.udemy.com/course/react-three-fiber-configurator/
I guess what a really want is a realistic mockup with a real human being model with it. Thank you guys for your replies… 
it would be the same, doesn’t matter what the shape is
You can easily do this with https://dynamicmockups.com
They have a pretty simple but powerful API where they allow you to use your own custom Photoshop Mockups.
Redbubble use ImageMagick composites of multiple layers (base, artwork & overlay) for simple flat mockups.
For more complex mockups like above as well as mugs, shower curtains, Throw Pillows etc, they use a custom Service created with Blender to map the artwork on to a 3D model, then use the same ImageMagick process as above.
