25 layers

1-Aramid fibers have High Strength to Weight Ratio Kevlar® is very strong and is slightly stronger than Carbon Fiber per unit weight.

Not all rubber is made the same. Rubber can stop some rounds (depending on the thickness) but usually not. The rubber allows the bullets to pass through it and then strike a hard surface. Then its energy and original shape are lost so it safely comes to rest between the rubber and the hard surface (usually steel).

Fiberglass is good at puncture resistance. They don’t say layers of what wieght or type they use, but it is possible. 9mm bullets if they are lead have little penetration on hard surfaces.

Here’s what I did find, though: At the low end of the scale, type IIA armor has to protect against smaller handgun bullets (typically 9mm full metal jacketed bullets weighing 8.0g or 0.3 oz and fired at about 373 m/s or 834 mph); you need at least 16 layers of Kevlar for that.

Also known as Opaque Armor, Bullet-Resistant Fiberglass is a layered, reinforced structural polyester laminate (fiberglass) that offers unique bulletproof characteristics.

A bullet can penetrate kevlar by pressing at the spaces between the threads. This will make it much harder for a bullet to penetrate. This and going with the epoxy resin coating and weighting five or so layers will probably yield enough resistance in of itself to stop most conventional pistol calibers.

This rapid cooling “freezes in” solid state solution of carbon atoms in the iron matrix and forms twisted ferritic cubical crystals. The twisted crystals give a very high strength. That twisted cubical version of iron crystals are called martensite, thus the name “martensitic armour steels”.