How to buy armour steel ?

1.What protection level do I need?What type of ammunition (M2AP，AK47，M80，SS109, M193 ,etc)?

2.What weight can the steel be allowed to have? Is there a weight limit for the protected product?

3.What cost can I pay? Can I choose more expensive 550 Brinell or 600 Brinell type armour steel than 500 Brinell?

4.Waht size do I need?

5.How shall the steel be fabricated? We must consider Cutting, welding and bending of the material

6.Do I need goods in stock or customized goods?Is my order quantity big enough ? do I have time to buy customized products? do I need to buy from stock?which one saves money?