You can print on just about anything. Here at The Drawing Board we have printed pens, T shirts and mugs over the years, and more besides.
And there is no limit really. Other than the technology required. But these days you can print on most materials, and at any size. For the visit a few years ago of Aung San Suu Kyi, Amnesty produced a large banner which was hung off Liberty Hall in Dublin.
I couldn't tell you how big this banner was, but it's huge.
Former Lord Mayor Andrew Montague and current chair of Amnesty Ireland, Colm O'Gorman, in front of Liberty Hall, Dublin.