I'd say you have a lot to learn yet. Yes you can use small sections in a wind tunnel. But to do so at Reynolds numbers that are meaningful you need to raise the speed or static air pressure in the wind tunnel for the results to be useful for larger models or full size aircraft.

And buying wings from other models is seldom going to provide you with true airfoils that you can call by name. Unless you build it using parameters you know you can trust and can measure them to ensure the sections are within less than 1% of truly shaped you really don't have what you think you have.