| j b 200 |
I guess it depends on the meaning of the word "Can".
An eidolon can use a shield in that they are physically capable of using a shield if 1) they have hands and 2) they are proficient in shields.
Obviously if we are talking about a Bipedal eidolon, it already has hands and even another form, hands can be purchased with the Limbs evolution at the cost of 2 evo-points.
Eidolons are not proficient in any weapons, nor armor or shields. To gain weapon proficiency the eidolon can either take a feat or the Weapon Training evolution (again 2 pts). You can only gain armor/shield proficiency by taking the requisite feats.
So to answer your question:
An Eidolon that has hands either from an evolution or base form, and has taking the shield proficiency feat, can use shields.