I use Masking Tape - and make it into H shapes
The Vertical strips of the H attach the tape (and Paper) to the wall in the normal manner
The Horizontal bar of the H has the tape reversed - sticky side out - to attach it to the back of the paper.
6 or 8 H shapes will stick a 20x16 piece of paper to the wall - and the you can get 5+ pieces of paper hung before the tape starts to loose its edge.
I wouldn't want to print professionally like this - but for the odd print - its easy, cheap and makes no mess.