Substracting many objects from a single object I am trying to recreate this wall with somewhat complicated indentations. I figured out the math and it's 8.75m wide, and it has 17 diviosions horizontally. I made a 17x5 grid of the "empty" that would be needed to be "removed" from the wall, to go from a parallelepiped to the wall full of holes. However, I'm not sure how to actually make the cut. I tried boolean substraction, but I can't seem to get it to work, it looks like it can only be done on two objects at once, but  I'm not sure how to join them all. I assume boolean addition might work one by one, but there must be a faster way
[
After you've created all the objects you want to "remove" from the wall, Join them. (Control + J in Blender 2.79).  Then you only have two objects, and you can do the Boolean subtraction operation.