You mean with wrench events?
Easy.
-Make a brick the size of a door. (4 width 5 height)
-Wrench it and click on the "Events" button.
-Click on the little "x" button 2 times.
-Click on the first little box that appeared when you pressed the "x" button.
-Click on "Wait For" and then in the box that pops up with the word "Triggered", click on it, and change it to "touch".
-Then, click ok and go to the second box that appeared when you pressed the "x" button.
-Click on "door", and then check off at least one of the points it has.
Then click ok, ok again, then send.
After this, you should be able to walk up to it and it will explode, de-collide or become invisible.
Hope this helped.
