Create characteristic using an existing product?

I have a client that has configured all her products in the shop and the shop has been running for about a year now.

Now she adds more products but the list just gets too long.
I adviced her to use characteristics instead of a product for all volumes.

Example:
It is a paint store, she sells 'white paint' in 0.5 / 1.0 / 2.0 and 5.0 litres.
She created a new product for each volume so the list of white paint in product listing looks like this:

- White paint 0.5l
- White paint 1.0l etc etc

I explained to her how to use characteristics and variants and that will definitly help her list to shrink.
Just one question:
Is there a way to use the existing products to create the characteristics and variants automatically?

The description and the photo's all differ per variant so to create new ones for all the products is a monster-job..

Help would be appreciated

Hi,
There is no option to transform your products into variants, so the best solution will probably be to export your product through a CSV file, to edit this CSV file so that you'll be able to import your products with variants with the good values.