I want advise wish scenario is most effective to represent my data

Table (A) fields:

ID (key), width (number), Height (number)

Table (B) fields:

ID (key), description (string), cost (number)

Table (A) which have the majority of the fundamental data only one record out of this table might have multi records from table (B)

For instance: record A2 might have B2, B2 while record A3 might have B2, B3, B4

Now must i use master / detail 1 to a lot of relation ? within this situation the consumer will repeat entering exactly the same "description" area from Table (B) for every similar value

or I ought to produce a third table (AB) to carry the attached data from both A and B ?

Thanks

within this situation the consumer will repeat entering exactly the same "description" area from Table (B) for every similar value

I'm not sure that which you mean with this but in my experience it appears just like a typical many to a lot of relation (A2 has B2, B2 and B2 has A2, A3). For the reason that situation, I recommend creating the 3rd "(AB)" table.