Addons and price unit

[briq]

Hello, I have a fairly difficult problem to solve and currently I don't know how to solve it without heavily modifying prestashop.

 

I have a ecommerce website that sells ropes, and those are often sold per meter. The only thing I've done to differentiate the products sold per meter and not piece is that there's a database of ropes and their corresponding "price unit" which is displayed to the custumer in the cart and product page.

 

Now to the problem: Each rope needs to have optional addons, not like lenght, width or color but more like accessories. This works when the products are sold per piece, then it's simply about creating combinations but when the rope is supposed to be sold per meter those addons should only affect the price once and not per every meter.

 

Any suggestions on how to solve this?

 

Thanks in advance // Sebastian