For this envelope is a standard piece of copy-paper used.
Step
1:I used a white piece of paper for this envelope.
Step 2:
Draw a help-line in the middle, see the blue line.
Step 3:
Make a valley-fold on the 2 corners.
Fold the edges of the corners to the help-line from
step 2.
Step 4:
Make these 2 valley-folds 2,3 centimeter or 0,9 inch
from the edge of the paper.
Step 5:
Add glue to the edges you made in step 4.
