Roger told me of his idea to build a wall on stage during the show and effectively aksed me whether it could be done. I did a series of drawings exploring the technical issues and produced visuals to suggest what it might look like. At the time, building a wall on stage as a performance progressed was without precedent in terms of scale and originality, but I never doubted that it could be done. The main consideration for me as a designer was how best to accomplish the task without the technology compromising any of the creative / philosophical ideas of the show.
The Wall was a more ambitious project than had previously been attempted and therefore entailed more kit, but all that really meant was that there were larger versions of the same old problems. Often the solutions were surprisingly simple. We all thought, for example, that when Gerald Scarfe's animation was projected onto the wall it would be better served by special paint. I tested a whole lot of bizarrely exotic variations, but in the end discovered that household while emulsion was far and away the best of the lot for our purposes.
During rehearsals, Roger continually sought to improve the presentation, but once we were locked in at the LA Sports Arena there were no further changes. The crucial thing during the shows was timing (the people building the wall were always racing with the band to get to the end of the first half), although occasionally something else would go temporarily awry. During one performance someone bumped into the wall and knocked a section of it down only a few minutes before the intermission so that the bricklayers had to work like hell to catch up.
Nothing really serious broke down and nobody was hurt. The opening night when a truss caught fire was a bit wacky, but that was dealt with quickly and all of us were hugely entertained the next day when the press wrote it up as if it has been a deliberate and remarkable special effect.
Probably because they were unique at the time, the shows have acquired a couple of myths. One is that they were enormously expensive to mount, the other that they were nigh impossible to tour. There's no doubt that they were expensive and that they were a pig to move around. The equipment, staging, etc certainly took longer than most to load in (generally it was about two days), but once everything was in that was it for a week because the Floyd were able to sell out in any arena for any number of nights. Obviously, that goes a long way to ameliorate the initial costs, as well as the logistics of shifting equipment.
The show was a landmark -- it's one of those things that is marvellous to lock away in the memory. It should be remembered with satisfaction and pride.