Step 1:
Take a piece of tin foil and a square black paper

Step 6:
Prefold over this line.
Then turn the paper.

Step 5:
Tape both papers together

Step 2:
Fold the tin foil around the edges of the black paper.

Step 4:
Fold over the prefolded lines.

Step 3:
Remove the black paper

Step 10:
Press these two edges against each other by folding over the red lines.
Do the same at the bottom right.

Step 8:
Valley-fold over these two lines.

Step 9:
Unfold the model.

Step 7:
Valley-fold over these two lines

Step 16:
Valley-fold over these two lines.
Turn the model again

Step 15:
Mountain-fold over these two lines.
Then turn the model

Step 12:
Valley-fold over these two lines.

Step 11:
Valley-fold both flaps downwards.

Step 14:
Make an inside reverse fold on these two places. The short lines are mountain-folds.

Step 13:
Pull both flaps to the right.

Step 21:
Repeat step 20 on these two edges.
Turn the model again.

Step 19:
Prefold over the two red lines.
And slide the end on the right under the edge indicated by the arrow.

Step 20:
Mountain-fold over these two prefolded lines.

Step 18:
Press the model flat on these two spots and mountain-fold over the red line.
Turn the model again.

Step 17:
Valley-fold both edges outwards.

Step 22:
Make an inside reverse fold on these two edges. Do the same on the edges at the other side of the model.