I usually start my search at https://www.daysoftheyear.com, choose one that I can think of a way to integrate a ₿ bitcoin symbol into a picture of.

Objects, like food (1, 2, 3), are easier to do than events (like World Kindness Day, International Tongue Twister Day, or Freethought Day), so that's why I usually choose a food-of-the-day.

I then look at photos associated with the targeted day until I have an idea of how to create an artwork that blends the ₿ symbol with that day's theme.

Once I have an idea of what I think might work well, I use generative AI tools to craft an image. I can't recommend any particular one really since the whole technology is so rapidly changing that which one I use varies from day to day. https://bing.com/create does a great job for the best price: free.

Then I will enhance the generation to make it look more crisp. There are many enhancing tools out there, but I frequently use this one since it does a good job for most.