These days, we live in an era where you can create your own illustrations or merch designs with just a click.

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In the past, you had to pay for a commission to get something like this made. Now, with high-quality AI tools like Nano Banana, most people use that instead. It’s free, and you can ask for revisions without feeling pressured.

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I also like making different things with my own game character from time to time.

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So today, I’d like to recommend a few ideas.

How to Use Nano Banana

You can use Nano Banana by entering requests in Google Gemini just like you would in a normal chat.

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Just click 'Create image' right below the chat box, then type whatever you want into the prompt field.

If you want to use your game character as reference material, you can drag a screenshot file into the browser or click the + button to upload it.

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For more stable results, it also helps to include the character’s appearance, outfit, background, camera angle, and overall mood.

Category	Nano Banana (Basic)	Nano Banana Pro
Base model	Gemini 2.5 Flash Image	Gemini 3 Pro Image
Resolution	Usually outputs around 1K, mainly at 1024×1024	Supports high resolutions up to 2K and 4K, so it works well for print and detailed shots
Generation focus	Prioritizes speed and lightweight output, making it good for idea sketches and casual use	Prioritizes quality, detail, and text accuracy, making it better for final results
Text rendering	Basic text rendering	Greatly reduces broken fingers and garbled text, with stronger multilingual text rendering
Compositing ability	Best for simple edits and compositing	Optimized for combining multiple images and building complex scenes
Character consistency	Average	Better at keeping characters consistent across multiple people and multiple shots
Creative control	Basic prompt-based control	Supports detailed “studio-grade” control, including camera angles, lighting, color correction, and depth of field
Best use cases	Thumbnail drafts, idea sketches, and light editing	Commercial banners, brand images, printed materials, product detail images, and campaign visuals

I also put together a quick summary of the differences between the standard model and Nano Banana Pro.

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You can use Pro for free too, but the quota is lower than with the paid subscription.

To use the Pro model, just select Pro from the model options on the right.

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If you want to make sure, ask for 4K resolution in the prompt.

Then, while it’s loading, you’ll see Nano Banana Pro, and you can also confirm the model by clicking the More button.

Phone Decoration Sticker Prompt

For phone decoration stickers, you can get decent results just by defining the style, composition, linework, background, and whether to include text.

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Using the screenshot above, I entered the prompt below.

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I used the standard model for faster results.

Turn the character in the uploaded screenshot into a phone decoration sticker illustration for customizing a smartphone.

Show the character’s full body on screen, and remove all elements such as the game background, UI, text, HP bar, and minimap.

Add a thick white outline around the character so it looks like a real sticker.

Make the background pure white, and keep background patterns, shadows, and lighting effects to a minimum.

Create it as a high-resolution 1:1 phone decoration sticker image.

This was the result.

As you can see, it cleanly removed the character nickname, title, in-game icons, and even the background.

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The quality is good enough that you could stick it right on the back of your phone.

This time, let’s ask for multiple phone decoration stickers from one character, like a set of emoticons.

Based on the character in the uploaded screenshot, create a 6-piece set of phone decoration stickers for customizing a smartphone.

Keep the character’s hair, outfit, and colors consistent with the original character, and use the following emotions and poses for each sticker.

① Victory pose, confident expression

② Defeat/mental breakdown expression, collapsed sitting pose

③ Surprised pose with wide eyes

④ Focused gaming pose

⑤ Cute pose sending a heart

⑥ Angry pose like rage gauge MAX

Render all stickers in a kawaii/SD style, with bold clean outlines and simple cel shading

Give each character enough empty space around them and a thick white outline, and unify the background as either all white or a very light solid color

Do not include game UI, numbers, text, logos, or watermarks under any circumstances.

Use a 9:16 vertical ratio that works well for smartphone backgrounds, and make each sticker usable separately

This was the result.

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If you want a design that looks closer to the original, just remove “kawaii/SD style” from the middle of the prompt.

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You can freely change the character’s poses and expressions too.

Other Prompt Recommendations

Standard model

Pro model. The detail is definitely better.

Turn this game character into a 1/7 scale figure.

Place the figure on a desk, with the packaging box behind it.

Use the attached logo as the game logo on the packaging box.

The character has clouds around their feet.

The character’s name is NEOPHIL.

Nano Banana can create plenty of other types of merch too. In fact, figures were what it first became known for.

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I also tried making a 1/7 scale figure with the prompt above.

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When writing a prompt, it helps to add extra clarification for anything the AI might misunderstand.

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For example, with the character above, it kept treating the cloud near the feet as part of the outfit, so I clarified that it was a cloud.

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The same goes for things like the number of tails or hair colors that might be a bit ambiguous.

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Since it tends to put a BANDAI logo and a random name on the packaging box, you should upload the game logo too and tell it the character’s name.

You can also simply ask it to remove the packaging box entirely.

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I forgot to ask for the cloud here, but it still turned out fine.

Nano Blocks

LEGO

Nendoroid SD Figure

Transparent Acrylic Stand

Heart-Shaped Keyring

Using this method, I tried making a variety of different merch items.

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For keyrings, you’re not limited to heart shapes. Round and square versions also work, and they usually look better if you ask for the character’s face to be made larger.

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You can also make things like can badges and Smart Tok grips.

Wrapping Up

That wraps up my summary of Nano Banana prompts and how to use them.

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At first, I just tried it for fun, but once I actually started making things, I felt even more attached to my character.

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Going forward, I want to put more care into character customization and keep having fun making all kinds of merch.