I noticed that in some of the maps, mostly the official ones, that when I try to sneak out a cube or some rubbage like the radio, or the the discs, or the computer towers, that there is some invisible feild that prevents me from taking them even close to the fizzler infront of the turbine elevator. I have no idea why they chose to put that in there when there is a perfectly good fizzler waiting to destroy everything that it touches.

However I do have this one place in my map i can definitely use such an element and was wondering how can I recreate it? I want to decompile a map to find out, but I can't remember where i saw this

Are you talking about an invisible fizzler or an invisible wall that simply blocks models from passing through? You can make an invisible fizzler by unchecking the "Visible" flag of a trigger_portal_cleanser. You can make an invisible collision by using a func_clip_vphysics with an appropriate filter.

the second one, thanks

It's in the exit door instance for no apparent reason. I found it while beta-testing A Beam Too Far, but didn't know it was in the original game too.