custom property set in ubercart3

Please help me with some advice

In Ubercart 3, there is a default set of properties: length, width, height, weight. I would like to create my own set of properties; what do I need to do for that?

There is a table uc_product_features in MySQL, but it is empty, and after adding fields using CCK, nothing appears in it.

In the uc_products table, the default properties are represented as fields. Adding new similar fields doesn't seem like the best solution to me.

I would be fine with an option that involves connecting a specific module. If you know the name, please recommend it.