I need to design a thick slit, in which i will place a lever, kind of like a large power switch that mad scientists have. I was wondering how to make the slit, and save as one mesh. Would really help if someone could tell me how to make the lever as well.
You can also use the Boolean modifier. This works great cause it makes the trench the exact size of the object embedded in it.
Create the objects, if needed create a separate object that is the size and shape you want your trench to be, the add a Boolean modifier to the block, with the handle or trench object as the target and the type set to difference.
Here are pictures of two different "evil genius switch's" (that a thing now :) made using the Boolean modifier.