This question rests on a false premise: It assumes there exists something – the building materials for a wall – that is outside of God’s own existence. That is, God is here, the bricks are over there, and you’re asking if God, Who has no physical dimensions and is unlimited, can then impose upon Himself both dimensions and limits.
It would be quicker to ask, “Can God be something other than God?” This is only a little different from Russell’s paradox, “Is there a set of all sets that do not contain themselves?” Rather than saying something meaningful about such sets, the paradox reveals that such a question is simply not logical.