bottomless pit

for the two way mirror effect you need a box at least 2 feet high and whatever your desired width, on the bottom is a regular mirror facing up - on the top i used 1/4 plexi with a "privacy mirror" film purchased at lowes adhered onto it - if you are wanting them to be able to look through the floor of the elevator, the elevator will have to be on top of the box - meaning that the people will have to go on either a ramp or stairs to get up to the elevator - or i suppose if your outside you could dig i gian hole and drop it in which i wouldnt do - but just threw it out there - - - i guess im not really understanding why you would want to do the pit effect like you have described - if this is an elevator - even if its a frieght one, it would probably have a solid floor - and if it didn't it would have a small hole grid made out of some sort of metal - which could eaily be replicated but will make it nearly impossible to make the pit effect actually visible - if you want to go the elevator route - why not make the first elevator shaft look like it actually already fell through and now all that is left is a open hole/shaft with a few pieces of old wood making a makeshift bridge that you have to go over top the shaft - then the second one will make them think they are going to fall to their deaths like the people on the first elevator - just a suggestion

i know the thick clear material that you can actually walk on is very expensive - its like 1 in or something like the clear basketball backboards - so unles you got a lot of $ id stick with the plexi - thats already not going to be cheap - you cant use glass though on the offchance someone trips and falls on the glass or something falls on it and shatters it