Boolean Difference?
 

I did a boolean difference once then tried using the same object with a different object but both disappear.

Essentially
Say I had a Polygonal cube A and did a boolean difference to take a chunk out of it with Polygonal cube B then after that did it again with C, well when I did A boolean difference C it deleted everything?

Whenever you Boolean you actually create a new object. This is the object you would use if you wish to Boolean again, not the original. Box B is taken away from Box A, this gives you Boolean Surface C or something like that. To take away Box C from that you must choose the Boolean Surface and not Box A again. Hope this makes some sort of sense, and you must keep the original objects or you will lose everything. I just create a folder called Boolean trash and throw the items that have been used up into it. One nice thing about the booleans, you can select them, and then use one of the transform tools to affect the surface. So if you had cut a hole out of a box and decided it was too small, you can select that Boolean, then use the scale tool and the opening will grow :)

Darkon

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Thanks Darkon, as usual you are an immense help.