Step 1:The backside of this paper is completely black.
Mountain-fold over this line
Step 2:
Prefold over this line
Step 3:
Valley-fold over this line.
Step 4:
Valley-fold over this line
Step 5:
Unfold the folds of step 3 and 4
Step 6:
Valley-fold over this line
(Use the prefolded line of step 4 as guidance)
Step 7:
Fold the model in half over this line
Step 8:
Make a mountain-fold over the line at the left and
a valley-fold over the line at the right (the line at the right
is already prefolded)
Step 9:
Mountain-fold over this line, then, turn the model.
Step 10:
Valley-fold over this line.
Slide the edge indicated by the upper arrow under
the edge at the arrow below.
Step 11:
Mountain-fold over this line, make this fold
over the upper flap only.
Step 12:
Valley-fold over this line, make this fold over
the flap below.
Step 13:
Press the black piece open from the inside, see small arrow.
You can also try to make the black piece round by
pressing it inwards from aside, see larger arrows.
Step 14:
Mountain-fold over the upper layer of the corner.
Make a valley-fold at the same place over the layer below.
Done!
