Before ink-jet printers, people used pen plotters to make printouts of colour graphics from computers. The plotter was a central device for engineers, designers and architects who used computers in their work. But nowadays it’s nearly forgotten. My exhibit is a Roland DXY-990 eight-pen, flat-bed pen plotter connected to a modern laptop and making drawings. The pens are no longer available, so I’ve hacked up my own from old pen casings and new rollerball and felt-tip pens. I’ll be giving away the A3-sized drawings to visitors.