I found a used hardtop, but still need the hardware to install it on the car. These would be two "Spin-Lock Inserts", left and right. They should come with a stocky little bolt each to secure them in their wee sockets. If you have a 986 Boxster that once had a hardtop, these may still be there... I'd be glad to buy them!
Part numbers from BoxsterWiki:
986-563-713-02 (or 03?) insert, left, qty 1
986-563-714-02 (or 03?) insert, right, qty 1
999-219-041-00 fit bolts, qty 2
Here's a picture of what they look like, credit to Boxster.Wikia;
Norm