(everything in one table) is called EAV and is generally frowned upon

It is only frowned upon when there is another way. Such as, when all attributes are static. If there's only one value per attribute, it would go in the main table, if there are many, they would each get a child table. It is not the structure that needs to be flexible (that would likely be a bad use of an EAV) but that the attributes are unknown. Such as a translation table, where the translated items are unknown, as are the languages it will be translated into.

I got he impression that the attributes themselves are not static, which is why i suggested an EAV. If they are static, however, it would be frowned upon by the purists in this case.