Basically by repeatedly bashing up the desired part of your body it begins to grow back tougher until it's pretty rock solid. Over years you end up with clubs on the end of yours arms. I'll hand you over to this delightful Chinese man who'll explain further:
What is the Iron Palm in Kung Fu? -- powered by ExpertVillage.com
Wasn't he lovely? Lovely, but also DEADLY!
Anyway, me being me I decided what my life was lacking was IRON HANDS! Although I chose my knuckles over my palms as a) I have a bad wrist and hitting things with my palm hurts and b) because I need to keep my palms soft for sensual massage. So I began my iron fist training. I'm going to write a full article on it soon but here's how it's going so far:
So not that well... but fear not! For the next stage, after pummelling your hands each day (I'm using a tough leather punching bag with no gloves) is to apply 'Dit Da Jow'. A strange herbal remedy from the East that will sooth and heal them each day. The ingredients for this should you wish to follow in my stead are:
1 bottle of strong vodka, gin or Chinese rice wine
Artemesia (Liu ji nu) - 5g
Borneol (Bingpian) - 1g
Carthamus (Honghua) - 5g
Catechu (Ercha) - 8g
Cinnabar (Zhusha) - 5g
Cirsium (DaJi) - 1g
Dragon's Blood (Xuejie) - 30g
Mastic (Ruxiang) - 5g
Musk (Shexiang) - 1g
Myrrh (Moyao) - 5g
Pinellia (ShengBanXia) - 5g
Sadly I have less Dragon's Blood hanging around the place than I'd hoped... and so after further research I learned I can use Tiger Balm - which I can also make myself woo! Instructions:
'Take a small jar of Vaseline, a small jar of Vicks, cayenne red pepper (it's somewhere in the kitchen on your spice rack) and either dried red chilli peppers (most gourmet stores have them) or red chilli peppers that have already been bottled.
Put the Vaseline in a pot and melt it on the stove at low heat.
Add two or three tablespoons of Vicks--depending on how smelly and mentholly you want it--until that also is melted.
Grind up the red pepper until it's a powder, mix it with the cayenne pepper and add to the melted Vaseline.
While in its liquid state, repour it back into a jar and let cool.'
(Thanks to Kenponet.com for this)
I'm staying at my Mum's this week - she won't be happy when she gets home to find me melting vaseline (she already suspects I'm insane)... ah well.
So basically if you want to BECOME IRON just pick a body part and beat it against a punching bag, tree, bag of sand etc for a few hours each day and apply the Dit Da Jow or Tiger Balm after each session. Who knows how long this is supposed to take... I'll get back to you with the full article shortly. Good luck!