You’ll be cutting out 6 squares that are each 6" x 6" (15 cm x 15 cm), so your piece of cardboard will need to be at least 18" x 12" (45 cm x 30). If you can’t find a piece that big, then several pieces will work fine too.
Make sure you use a dark pen or marker. Otherwise, you may not be able to see your lines when you cut.
Wear gloves during this step to prevent paper cuts or any injuries for the scissors or box cutter.
Glue the edges of the cardboard together to form the cube. If the glue doesn’t seem to be making a strong seal, you can use strips of tape to secure the cube while the glue hardens.
Lay the square down flat and put glue around the edge. Then slowly lower the box onto the square, making sure the glue makes contact with all edges of the box.
Clear tape is the best choice here. Colored tape might throw off your designs when you decorate your box later on.
Craft or hardware stores usually have small magnets that are meant to hold boxes or cabinets closed. Looking for these should give you a good start. Remember to find out which sides of the magnets attract each other. Those are the two sides you’ll line up when making your seal.
To find the right position for the second magnet, start by closing the box slowly. This way you’ll be able to see where the magnet will rest when the box is sealed. The best place for the second magnet is right under that point, so the two magnets touch when the lid is closed.
Compression springs come in lots of sizes. For this project, you’ll want one that’s slightly taller than the box, or about 7 inches (18 cm). Your local craft store should have plenty of options. [10] X Research source Test the seal by making sure the box stays closed when the spring is in place. If the box doesn’t stay closed, your spring is too big or your seal is too loose.
You could also draw and cut out a simple face from a piece of paper and glue it to the top of the spring for a simpler design. [12] X Research source
