Nails are the first Commercial material unlocked in the game. It is available from Level 1 in the Building Supplies Store. The Building Supplies Store is unlocked at Level 1, the first commercial building to be unlocked.
A nail can be produced in 5 minutes in 2 stages without using the Global Trade HQ or a Speed-Up Token. Based on this production time, the simoleons/minute is 16. (High-tech Factories and 3-star shops were used for these calculations.)