I use a bag of steel shot to train my iron palm.

I have other various sized bags to train my claws, by grabbing bags I toss up as well as play catch with a partner.

I also train my grip strength as your hands will love you for it.

I use COC(Captains of Crush) grippers as well as plate loading grip machine to blast my lower arms.

I still train my iron palm, though I seem to gravitate toward more qi gong like Royal Dragon, maybe thats a natural progression.

Dale