We have a full size plastic template that the artist made that we layout and determine the location where we want to paint black splatter. The template is just a big sheet of clear plastic with a magic marker out line of the painted part of the piece. Since the template is considered to be part of the object we can't cut, draw or paint on it. So what we do is once we have it positioned we project an image of the finished piece and use the template to locate and size the projection.
Once that is done we take down the template and draw the out line of the splatter with pencil onto the wall. Once it is drawn onto the wall the curator will decide how it has to be modified to fit the space it is being installed in. These changes are then run by the artist.