This astrolabe is the only one which I found in the Ashmolean Museum. It was probably made in Spain in 1260 and it’s lent by the Museum of the History of Science.
Finally, I noticed two game boards. The first is this bone, wood and horn board with chess on one side and backgammon on the other. It’s from Northern Italy (1420-1450):
The second one is also from Northern Italy and the same period and it’s a chessboard on one side and a game involving moving pieces along the coiled body of a dragon on the other:
And that’s all! I’m sure that there are more mathematical objects in the Ashmolean but… I didn’t find them. If you do, perhaps we can collaborate in another post!