What is the best DIY seat that also serves as storage?

I have a a storage cube that also serves and a seat but it is hard to move around. I have magazines and board games in there and it's a pain to move.
The way it is constructed it isn't ideal to put wheels on it or at least I don't know the best way to do that.
Update: The one i have is one of those cheap options from Walmart.
Update 2: I have found some but there are no instructions for them or measurements. I really like full instructions as I tend to mess things up when I wing it.
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