"It would be made much stronger however."

I'm not sure about storing much in it but for forearms you don't really need it to be much tougher than a set of good quality soccer shinguard. I know this from a local bouncer who started wearing fiber-reinforced shin guards on his forearms after a fight where he tried to block a bad stool and had his arm broken.

Now he says he has a lot confidence in these simple glass reinforced nylon units. As an experiment a friend swung a baseball bat and he easily blocked it without so much as a bruise.

These units are thick translucent nylon with a glass reinforced stripe down the middle. He says he used a jigsaw to modify the shin guards to fit on his forearms. He wears them under a long-sleeve shirt. He also wears matching shinguard. When a drunken free-for-alls break out the guys typically like to swing the furniture and the ladies like to abuse the shins. He also wears lifters gloves.

I'm not sure I qualify as a person who really needs such gear. I tend to avoid crowds. But if your plans or habits put you in situations where fisticuffs or pounding through a crowd is likely I think a sturdy version of the athletic guards on shins and forearms, otherwise known as greaves and vambraces, sound like a good idea.

You might find the lighter plastic version lighter, more comfortable and plenty strong enough. You might look into the armor commonly worn by guards for prisoner extraction. Fully armored up they look like imperial storm troopers.