Design and build the drawing area for the main performance

[amcewen]

Following the site visit (issue #19) we think it'll make most sense to hang a plywood screen off the scaffolding poles for the main performance polargraph.

For the main performance area - the projector screen can't easily be moved (and Lizzie has some photos she'd like to project onto it anyway). We think the best approach is going to be to hang the drawing area to the left of the screen (when looking at it from the audience, like in https://www.flickr.com/photos/amcewen/24811058904/in/album-72157664813872800/). There are hefty scaffold poles mounted vertically (as can be seen in https://www.flickr.com/photos/amcewen/25415458676/in/album-72157664813872800/ although those are to the right of the screen) which are 48mm diameter. The ones to the left are 10 feet apart, so we could fairly easily hang a full size sheet of plywood between them. We need to avoid the fire exit, but that's unlikely to be a problem. The venue have the right kit to get access to them to do the hanging. It's probably best to build it as a self-contained unit just needing power, as it'll be trickier (although not impossible) to have things on the floor below it (particularly on the left side, as that'll be off the edge of the stage and near the fire exit)

If we're doing that, (I think) it makes sense for the servo motors to be mounted directly to the screen, in which case we wouldn't need the second set of corner pulleys from issue #13, and the servo mounts in issue #3 would need to fasten onto the screen too.

[amcewen]

This is being covered by the OnShape model in issue #32