Leaps of Logic Demo
oh yes, you would be trapped inside with all four cubes. The ball catcher is a less than elegant solution though, if the test chamber is entirely metal except the last two rooms, you'd be able to portal in there, if only you had a portal gun.
I'll explain my thought processes with the second part
I started making the second part at the same time as the first part, because a good friend of mine (goes by the name KingKoolKyle on the internet) designed the level on graph paper and I liked it. It went rather well until the end, where in testing I found that you would be trapped without a portalgun, but it would be broken with a portalgun, and I liked the way it looked in concrete. So his recommendation was to make the catcher hold the door open, which worked well. From my experience with Ad Hoc, it's hard to get a door to stay open when the buttons still work, so that's why I disabled the buttons.
About the signage, I will have better signage in the final map. The demo is for demonstrating 1) what the logic gates do and 2) how they could be used to create a complicated puzzle. With the final map I will include an updated demo with better signage and more of the gates demostrated. It will be recommended that you play the demo before the actual map, because I won't have a learning curve for the map. The reason I included no signage in the second part of the demo was because I wasn't sure if that's how I would use the signage in the final, and since most of the gates were AND gates there wasn't really much point in posting AND everywhere.
If someone wants to take a crack at designing signage, I can send you some poorly drawn guides I made for myself detailing how each gate is used.