My younger brother was a techie during his high school years!
What did he do? Most of my experience was with the properties crews, but I also had experience with the costume crew, filled in a few times for stage crew during rehearsals when they needed a spare pair of hands or someone to act as a "gofer" - necessary when many of the same people were involved in both The Music Man and A Dish of Cream when they were rehearsing at the same time in different studios, and I've done front of house (one of the perks of that is seeing the show for free if there are any unsold seats).
Back in the '90s a friend called and said, "We're doing
Man of La Mancha, would you like to be in charge of the props crew?" I had to turn them down, since by that time I had two home businesses going and my free time was taken up by the mundane aspects of the Society for Creative Anachronism (by that time I was doing the bookkeeping, putting out the monthly newsletter, and liaising with the media - the branch was fairly small at that point so all of us had to wear at least one hat and sometimes several). But I did get to be part of it in a limited way. I offered the services of our SCA group to do front of house on opening night - and we would all be in costume.
It was something different for the rest of the group. They'd never done front of house before, and a couple of them were a bit dubious until I told them that it involved taking tickets, handing out programs, and for those who were assigned to be ushers, "you get to tell people where to go" (escort them to their seats). It was a fun night, the show was excellent, and the review in the newspaper was glowing - and mentioned that the front of house people were in period costume. I sometimes wonder if there were any audience members who were disappointed on the other nights when the front of house people were dressed in 20th century clothes.
We did front of house at Red Deer College as well a few times - once for a concert and twice for Shakespeare plays (
Romeo and Juliet and
Macbeth). It was a bit odd at the concert, since some people in the audience refused to believe that we weren't actually performers ("Are you SURE?")!
One of my favorite costumed theatre experiences, though, was when the movie
First Knight opened. This is the only Arthurian movie I've seen that does NOT include Merlin, Mordred, or Morgan (the villain's name did begin with "M", though - Sir Malagant). It starred Sean Connery and Richard Gere, and it's my favorite Arthurian movie. The theatre contacted us and asked if we'd be interested in doing a costumed demo at the theatre before the movie started. We ended up putting up a display in the lobby and some of our fencers put on a demonstration at the front of the theatre before they started the movie. In return for this, we got to see the movie for free.