Molded plastic toolcases and toolboxes are handy, but their snap together hinges sometimes come unhinged. I have one such toolbox that would unhinge each time I opened the lid. See the second photo. Getting the hinge parts back together usually requires two hands and is an annoyance. This Instructable shows my solution to the problem.

Step 1: Drill Holes in the Case

Drill a small diameter hole above and below each hinge nearest to the outside edge of the toolcase or toolbox. Some plastic toolboxes have more than two hinges, but if this modification is made to those hinges nearest to the hinges farthest left and farthest right, that will be sufficient.

On many toolboxes and toolcases there is room between the hinge and part of the box to pass a wire. This makes for a tighter reinforcement of the hinge and means only one hole must be drilled. See step 7.

Tools

Needlenose pliers and wire cutter
Drill and small bit

Materials

Thin steel wire about 22 gauge

Step 2: Push Wire Through the First Hole

Open the case and push the wire through one of the holes from the inside.

Step 3: Push the Wire Through the Other Hole

Make a "C" bend in the wire and push the end through the other hole. Do this for both hinges.

Step 4: Cut the Wire

Leave the wire ends a little long. Cut the wire.

Step 5: Begin to Twist the Wire

Make a twist in the two wire ends, but leave the twist away from the hinge. Open and close the case to make certain the lid moves freely without the wire binding or becoming tight. Move the twist if necessary.

Step 6: Finish Twisting

Finish twisting the wire ends together. Bend the twisted ends over to keep them out of the way as much as possible. Try to make the ends so they will not scratch hands or stab fingers.

When finished, the wire loops should be tight enough that the hinges cannot unhinge, but loose enough that the lid of the toolcase or toolbox has free movement. These wire loops will make your toolcases and toolboxes much easier and less frustrating to use.

Step 7: One Hole, Tighter Wrap

If there is space between the hinge frame and one half of the toolbox, drilling one hole only and wrapping the wire more tightly around the hinge and its pin is ideal. This is another toolbox than the one shown in the introduction. It was very bad about unhinging every time I opened it. There was space to wrap the wire more tightly around the hinge. Now the hinges work just fine.