Making canvas

canvas (n.)

"sturdy cloth made from hemp or flax," mid-14c., from Anglo-French canevaz, Old North French canevach, Old French chanevaz "canvas," literally "made of hemp, hempen," noun use of Vulgar Latin adjective *cannapaceus "made of hemp," from Latin cannabis, from Greek kannabis "hemp," a Scythian or Thracian word (see cannabis). 

The idea of hemp for crafts, mostly rope.  But also including hemp stalks woven together for a patio wall. The word likely predating weaving. This is an old word.  Hemp was evidently a hand workable material for a longtime.

Hemp plus a light weight clay and supporting fish net; add the supporting frame, you get a canvas art form, and a very primitive paper.  Cross hemp layers, fibrous in both axis and dispense with the frame. You get sheets, stand alone. Like little post it notes.

But, if one was careful with the canvas, one could take it home, hang it on the wall. It might be a reproduction of a Latin verse from the parchment bible, but much cheaper, much less durable; like art.

Hemp in China:

"Cai Lun's" invention, recorded hundreds of years after it took place, is dated to 105 CE. The innovation is a type of paper made of mulberry and other bast fibres along with fishing nets, old rags, and hemp waste which reduced the cost of paper production, which prior to this, and later, in the West, depended solely on rags.^[6][7][1]

Demand sot up in China and Europe at the same time:

The production process may have originated from the practice of pounding and stirring rags in water, after which the matted fibres were collected on a mat. The bark of paper mulberry was particularly valued and high quality paper was developed in the late Han period using the bark of tan (檀; sandalwood). In the Eastern Jin period a fine bamboo screen-mould treated with insecticidal dye for permanence was used in papermaking. After printing was popularized during the Song dynasty the demand for paper grew substantially. In the year 1101, 1.5 million sheets of paper were sent to the capital.^[9] 

It was not unheard of, and even crappy paper should have had its uses. But suddenly demand?