Replying to Serious box building question

I wanted a good box so i built a very sturdy wood 12 foot box, counter-synced HDPE top sheets over it, and the only thing i have a question on is the metal edging.

1. Is it helpful to have the metal edging?
2. What type of metal stripping is recommended for the box edge?
3. How should i attach it to the HDPE?

Any other information would be helpful because theres a huge storm coming tonight and i want it done for tomorow! Thanks NS