I use these clasps - again, here are a couple of cheap types from ebay. I elected to pop-rivet these without spacers, and they squashed the twinflute material - ah, well...
Note the white spacers cut from plastic sheet. These bring the bottom half of the clasp out a little, to match the top connector.
Ideally, you want clasps where the top and bottom become a single unit, like these. The result is much stiffer than the clasps which simply pull the two parts close together.
Here is one of the bottom clasps being put on...
And off we go to the pond...!
...giving a nice flat strap enabling boxes to be easily stacked if needed.
Now it's time to attach the clasps.
Holes are measured and drilled, and two bolts are passed through the hardboard to be secured with locknuts...
