Forced Items from Media Files

I sell blankets. In my products I have each blanket size (small, medium, large) and for each blanket size I have a weight variation so it ends up like this
small (2lbs, 5lbs)
medium (6lbs, 8lbs, 12lbs)
large (14 lbs, 18 lbs, 22lbs)

Easy enough…here’s the question

I need shoppers, once they have selected a size/weight to then select two different fabric patterns (for the front and back sides of the blankets) there is no additional cost for the fabrics but they MUST select 2 fabrics before it is considered a complete order.

Right now the fabrics are just media files (pictures) and not individual products. How can I force the selection of 2 fabrics from a gallery to go with each order (obviously if they order 2 or 4 blankets then I’ll need 4 or 6 fabric selections)

I am not a developer, but can handle plugins pretty well. Anyone know of anything already out there that could help, of if there is a way to do this directly in Woocommerce that would be great as well.

(FYI, there are far too many fabric choices to be able to photo every permutation)

Thanks in Advance