GeoMagnets, have you tried setting up a Product Template? From the inventory menu click on Product Template near the bottom of the list. Templates allow you to set up a variety of field types that can be used in multiple products (or just one). It can consist of one or more text boxes, drop downs, etc.
I use the text box to allow the customer to enter a personalization for ID tag engraving. You can set a character limit for the text box depending on the maximum characters allowed for the personalization. You can have as many rows of personalization as needed for the item.
After creating the Prod Template edit or create the product, click on the Template tab, and select the Product Template name from the drop down. Save the product listing and display the product to see how it looks.
There are some limitations with the Templates but they work pretty well especially if several products require the same fields (create it once, use it in as many products as needed.
Hope this helps!