In 2006, Roger Angel published “Feasibility of cooling the Earth with a cloud of small spacecraft near the inner Lagrange point (L1)”.  In 2012, Bewick and others proposed placing clouds of extraterrestrial dust at the L1 point.  The material could be mined from captured asteroids, being moved by solar collectors or mass drivers.  Dust for sunlight blocking might also be mined on the moon.  In 2020, a team at Massachusetts Institute of Technology proposed placing at the L1 point inflatable elastic bubbles made from liquid (image above).