That's cool...
Do you mind me asking where you find your art work from?
I'm struggling to find the box art. Thought I might try to do a couple myself, but no luck so far
Places I look for images:
1. USA, EU, and JP official websites for the game.
2. Official twitter account posts about the game/amiibo.
3. Reverse image search on the box art/Google image search for the game/character.
4. Wikis about the game.
5. Official newsletters from Nintendo about the game.
6. Media release portals / Media kits.
Usually you need a password to access these sites, but sometimes you can find re-uploads. That said, I think it’s only ever been helpful once, because it’s usually just basic product shots... but you might get lucky. In the past, they made their E3 media kits free for everyone by posting an E3-specific username and password for the public, but E3 is dead now, and it would only really help if the game/amiibo was promoted during that time of year anyway, but they might still do public access for large Nintendo Directs around June/the Summer Game Fest.
While you are looking for the character art you will want to also keep an eye out for other assets that appear on the packaging (like the background or dividing patterns/shapes). Sometimes you have to make those assets from scratch.
In all cases if I find an image I usually use reverse image search to find the highest quality version of the image, preferably with a transparent background.
Things to watch out for:
1. Upscaled low resolution images.
Don't just look at the size of the image because someone could have upscaled a low resolution image.
2. Finding an image that someone removed the background from themselves.
Sometimes people do good jobs removing the background from images but its very rare. It's always better if you can find images from Nintendo without the background. Most people use auto background removal tools that are garbage and miss sections. If I absolutely can't find a transparent image I would rather mask the image myself than use someones crappy image that probably has white halos or sections missing.
3. JPG artifacts.
You generally want to avoid the blocky artifacts created by the JPG algorithm. Ideally you want to find PNG files which use "lossless" compression. Sometimes people convert JPG images to PNG file formats but that will not remove the compression artifacts, so - like with resolution - you cant just rely on the file type, you should zoom in and check to make sure there are no artifacts.
4. WebP images.
These can be "lossless", like PNG, but they can also be "lossy", like JPG, depending on how they are saved, so again you'd have to check the image by zooming in.
5. Artifacts VS Resolution.
Sometimes a JPG at a higher resolution will look worse than a PNG at a slightly lower resolution depending on the level of compression in the JPG. Sometimes there are no high quality PNG source images so then it becomes better to use the higher resolution compressed JPG. You have to use your own discretion to decide which looks better.
6. Slightly different character art.
Sometimes there will be character art released that is very slightly different than the amiibo box art. This is more likely to happen if the amiibo are released later in the games life, like with the Sages. I generally try and overlap the art I find with a high quality image of the packaging image (usually easily found on retail websites) and then quickly toggle between the layers. This usually makes any small difference easier to notice as you flip between the images. If there is a difference, it can sometimes be harder to find the box-art version of the image because it’s newer, and they may not update the websites or produce much new promotional material that includes the revised artwork. In some cases, depending on what the differences are and where they appear, it may be easier to crop the differing area from the packaging image and composite it onto the higher-resolution version of the slightly incorrect character art.
