I first used 5*2 magnets in both the edges and corners which is very strong as the plastic is so thick. However, that was not even noticeable. Then, I stacked 4*2 magnets in both the edges and corners which can only barely fit in, especially for the corners, putting the magnets strength to a slightly stronger side. Make sure you do it on the same side of the corners and edges as it may result in not being able to fit in the additional magnets later on. I started it out on the side with a little bit more space as I wanted more room for the magnets in case additional magnets is needed, which turned out to be needed. I was inspired by a youtube video to magnetise the qiyi kibiminx, which I will link it below. In the video, 4*2 magnets are used and there are no additional magnets, so the magnet strength is pretty weak.
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