Removing External HD From Case

I plan to buy a 4 TB external hd, which, if possible, I would like to eventually remove from its casing and put into an external multiple hd bay which I'll purchase in future. I'm looking at the Seagate STBV4000100 hd or the WD WDBFJK0040HBK-NESN hd models. I realize this will void the warranty, natch, but is there any reason that doing this would be a problem? I mean, would I be able to open it with a screwdriver or am I going to have to break the darn case to get the hd out? And, if the latter, will I be able to do so without harming the hd? Thanks!

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