It really blows my mind to think of the things experimental physicists have accomplished and continue to accomplish. One example is molecular beam expitaxy (MBE) technology that lets researchers deposit layers of a material that are literally one atom thick. Another example is the work by the LIGO project to push mirror technology to limits that are hard to believe:
https://www.quantamagazine.org/to-make-the-perfect-mirror-ph...