The lock bolt is in the mailbox does not always withstand the encroachment of the feeder bullies. Too primitive its form is thin and the iron from which it is made.
But if you replace the stock bolt with steel plate cross-section 20×3 mm, bent as shown, so just the box, no one will open.
Recommend to read
KHARKIV MOTORCYCLES
By the early 1930s, one of the centers of the nascent Soviet motorcycle could be the city of Kharkov. Here in the capital of Soviet Ukraine, on the territory of the former sugar factory...
SCISSORS WITH RULER
They say: "measure twice — cut once", but if one of the shear blades to cause a spark or graviroval marker centimeter scale, as shown in the figure, from a preliminary marking in many...