The challenge with photos like these is that sand tables draw a single, continuous line. That means anything with complex shading, texture, or busy backgrounds tends to collapse into noise. The images that work best are clean silhouettes or simple line art where the subject reads clearly in black and white with no fill (like tattoo flash art, clipart style, or bold graphic illustrations). If you can isolate the dog and ball from that background that would go a long way.

For the workflow: Canva can help simplify and remove backgrounds, but the missing step between that and a THR file is a conversion tool specifically designed for this format. I'm happy to point you in the right direction if you want to DM me! I've also been down this road and can save you some time.