Cut off the bottom of the milk carton from 3cm above. Cut a strip off the remainder of the carton 3 cm above the bottom.
Cut so that they are similar to the picture. 2 strips.
Cut a notch halfway through from the top in the center of one strip, and do the same with the second strip from the bottom.
Insert the notches into each other to form partitions. Crease the strips so that they are interlocked in the center (as pictured).
Place the bottom of the carton underneath the partitions.
Place a bite-sized portion of rice on some plastic wrap.
Wrap it up.
Place it in the box. If only making one onigiri, move on to Step 12.
Do the same thing for the next onigiri.
Pack it in the box.
Put the next one in as well.
Make sure they're properly wrapped in the plastic wrap.
Push down on them gently but firmly, with your hands.
Flip the box over and remove the onigiri.
And they're done.
You can use as much nori as you want!
Easy Onigiri Rice Squares
Easy Rice Rectangles