This is a super super easy origami model designed by Jeremy Shafer. It is an ordinary envelope that unfolds when pulled and can easily be refolded for more exploding action.
Step 1: Supplies!
All you need for this is a square sheet of paper.
*i strongly recommend origami paper (any size). other types might affect whether it explodes correctly and it might rip easier*
Step 2: Fold in Half Diagonally
Step 3: Fold That Point Down
fold that corner down past the end crease by a little less than an inch and crease well.
Step 4: Fold Left and Right Corners
fold the corners so they meet the intersection. the will overlap
Step 5: Insert Point Into Flap
You will notice there are pockets in the two triangles.
insert one point left or right into the opposite flap. it doesn't matter which one you use. it will be the same.
Step 6: Fold Top Down
Fold the topmost corner down. go slightly past the the intersection of the two triangles.
crease well and you are done!
Step 7: How to 'explode' the Envelope
Just hold the middle of the top area.
also hold the little tab at the bottom.
and pull the tab down quickly with mild force.
if you pull too softly, the paper might move but not explode.
if you want, you can write something like BOOM or POP on the inside of your envelope
Step 8: How to Reload
Okay so, you exploded your envelope.
How do you put it back together? Just refolded along your previous creases, tuck the point in, and you are good to go!