Once you get a 3d printer, you do tend to find many uses for them for things you could easily buy (organizing bins and the like) but I don't think anyone is buying them with this in mind.
I built a four-poster bed, and 3D printed the fittings for the curtain rails and the attachment point for the fan.
I built a desk, and 3D printed the entire shelving system for it.
I designed and 3D printed an entire range of boardgaming accessories (storage bins, dice towers, meeples, etc)
I only bought the thing as something to do while in COVID lockdown. But it's been really useful.