Do I have to use parentheses when using or + and?

Yes. When using the operators or + and together and the search terms before and after the or belong together, you should enclose them with parentheses.
(3d printing or additive manufacturing) and construction

Without brackets, we go through the search phrase from left to right, and the and operator joins the search terms before and after it.
So a search for "3d printing or additive manufacturing and construction" will result in companies that either do
3d printing
or
additive manufacturing and construction.