Customer input fields on product page

I am selling products which are personalised for each customer, for example, a pendant which would be engraved with the customer's name. I need a way to enter one or more input boxes on each product page, where the customer can enter their name or preferred text (limited to a certain number of characters which will vary with each product), and to have this information passed to the checkout so that it displays in the order email. Is there an extension that would allow me to do this or is there a way to do this myself (I'm no programmer).

You can assign product option "text" to each product using catalog - product - edit - option
So this will have an input field added on product pages where customer can enter the text.
It does not have checking of number of characters per product.
You will need customization for this.