Do you think the Donald Trump wall is a good idea?

Do not.
It would be enormously expensive to build it, according to estimates, $ 26 billion.
Even more expensive to maintain.
And it would not be effective.

If there is a definition of pig hut in the dictionary, this wall would be.
You would not be surprised to discover that Trump or one of his children own or have shares in the construction company that would get the contract without bidding.