Oil thrower: (can be omitted) thousands of dollars.
Cleaning machine: It's also thousands of dollars.
Annealing furnace: (10W, which can be outsourced at first)
Polishing machine: (can be used with cleaning machine)
Nailing machine: (there are also different manufacturers and models to choose from) ranging from 3W to 6W.
Nail washer: (or nail roller, deburring) thousands of pieces.
Combination machine: at least one 3W machine, with at least three.
Laboratory testing equipment: (omitted, there are many testing items, and it costs a lot of money to equip the equipment, but at least one tension machine, which is also a few W, and always the cheapest 2W, 10W is good)
If you know how to do it, maybe you can save money in some places. I have seen a very small room, and I started to make products after disassembling a few machines. It is very simple and the investment should be very economical.