A cheap homemade metal rail?

well today in my 2nd grade classroom, i was talkin with my friend. and he told me about making a backyard metal rail, but for cheap. he told me that his friend did it (i know the friend so its legit) and it works just as great as any rail at the local mountian. he told me to mosey on down to lowes and buy a 2bi4 along with a roll of aluminum sheeting (flashing). well i believe that the flashing will work great and slide fine since ive slid aluminum bleachers before but i dont know how i should attach it to the wood. i was thinking of cutting it into a 10 foot by 6.5 inches and centering it on the wide part of the 2bi4 and bending the excess over the side, and then screwing that down on the bent over sides (if u didnt know 2 by 4s are really 1.5 by 3.5s, hence the 6.5 width) and before hand id lather on some silicon glue between the wood and metal. if needed ill make a pic in paint and attempt to post it. would this work or do i need another way of fastening it on to make it a good rail