casting on edge
Unroll some copper sheeting, crumple . . .
. . . with a rubber mallet. Zig zag the distressed material back and forth, duct taping a few of the zigs to zags on the bottom edges to keep it from getting out of control. Seam several sheets of 5 hr abaca end to end to make a sheet longer than the mold in order to have lots of material to drape between edges.
With the sheet held suspended . . .
drape it into position on the copper. Gently press/massage the sheet to round and smooth the valleys between the copper edges. The sheet is left taut and sharp over those edges. Those edges will dry crisp and thin, giving the sheet a remarkable structural stiffness.
Dribble in some pebbles and wait 4 days.
The pebbles keep the abaca taut and from shrinking up flat between the copper edges. They also slightly emboss the paper.