Why cant they make black boxes buoyant (floatable)?

This isnt the first time a jet has gone down in the ocean. If the black box is so important in finding, why dont they just make it buoyant or the area around it?
Update: Well it would be inside a section of the plane, thas what I mean when I say "the area around it". Why not just make that section of the plant buoyant? Well TKE's idea is more practical and probably easier too
Update 2: TKE, thats a better idea
Update 3: biking for life, I think that material is probably real heavy so it would make it harder for the flight to stay in the air.
Update 4: lol@stackwiz. I didnt even see your question. what a coincidence lol
Update 5: "However, a smashed "black box" isn't going to signal anything. Plus, it's at the bottom of the Atlantic, the signal is not going to be found unless you're right over it."
well if its smashed, then what good would it be for them to even bother looking for it?
Update 6: "It's a common misconception for people to think the black box remains fully in tact after a crash."

Wether it stays in tact or not, its obviously valuable enough for them to want to find it, so make the "pieces" of it buoyant then.
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