I meant DS, sorry; the 3DS didn't come out until 2011, well after the Pandora's design had been finalized. I'm not sure if the 3DS hinge is compatible or not; if you've got a spare go ahead and try it, worst that'll happen is it won't fit, but considering how simple of a part it is I can't imagine they'd bother changing it. You can easily buy a DS hinge off ebay for under $5 if it doesn't work.
Would this work?
http://www.vartis.de/product_info.php?info=p1448_Nintendo-DS-alt-Ersatzteil-Axxis.html