My vacuum easel is made as Henry suggests but instead of pegboard I used a board made of the same material and drilled smaller holes myself, like 1.5-2mm. The holes in pegboard are too big and cause noticeable dimpling marks in the paper. The vacuum cleaner is connected to a footswitch so that I can turn it on before exposure and off afterwards. Also was lucky enough to find some nails that fit through the holes and work well as pins for aligning the paper if I want to. My box is 12 x 18 inches. I have made thin cardboard frames to lay over the outer holes to concentrate the suction in the middle of the easel when using smaller sized paper. Been using this for about 5 years and it works quite well.

-- Jason