Photographers Grey-Card?

[Grandpappy]

I want to create an ' 18% exact ' grey card that I can then print on my HP printer using Photoshop?
My intention is to 'create' this card & then apply (in black),my contact details,eg. email address,phone number and then print it off and laminate it for the future.!
How do I do this?
Simplified instructions please or any constructional advice.
I know I can buy sheets of 18% grey card,but I'd prefer,if I can,to make it myself.
Once created I will then take the first shot of every formatted camera card, using my new ID card and hope, that if I do lose the camera card then someone will contact me!
It's worth trying.
Cheers

[bhg481]

You might upset the colour balance when you laminate it, as the laminate material will probably change the spectrum. You will also be dependent on your printer producing the card exactly to colour spec. The safest way would be to buy the grey card and keep it in an envelope, just taking it out to photograph it or set your camera colour balance.