Sure, they can build a MOSFET. But it will be pretty bad, you need to have a theory of operations before you can make reliable, powerful and small device we hav

Sure, they can build a MOSFET. But it will be pretty bad, you need to have a theory of operations before you can make reliable, powerful and small device we have today. In fact, a field effect transistor (the FET part of MOSFET) was discovered in 1925 and 1934, but nothing happened with it until the theory was there, and someone (Shockley) spent years refining the theory with experiments.