It might surprise you to learn sir, I once saw a mini bus' roof being built with wood and a whole lot of bondo (masilya).
It's no wonder they wreck easily, they're made from the cheapest materials they can scrounge.
I know, i saw a bus body being built using 2x4 wood, a lot of angle bars and flat bars, plus stainless sheets.
That was in the 90's. May mga branding na mga bus now di ba?