Old thread but I too am looking for ways to lock my toy box up for mast up storage on my trailer come spring. Read the hasps idea but pictures would help. Thanks.
I swear I took some pictures but I haven't been able to find them.
You need to lock the top opening and the rear/main opening. I put two hasps on the top opening and two on the rear/main opening. They aren't anywhere near 100% secure but I like to think that they deter someone from messing with it. On the top one I put one hasp on each side. One the rear/main one I put two hasps on the bottom left and right outside edges. As for hardware, I would suggest some kind of backing block because screws will easily pull out of the plastic.
I've considered doing away with the hasps and dropping a metal bar through the rear opening and locking on both sides of the bar. I've seen this on many sail tubes and it is the simplest and most effective method.