[AccessD] Flattening the results of a query

I have a query (Query1) that outputs as follows:

Cust1    Product1
Cust1    Product3
Cust2    Product9
Cust3    Product1
Cust3    Product2
Cust3    Product3
Cust3    Product4
Cust4    Product1
Cust4    Product2

And I want to flatten the results for output to a form so each line on the screen looks like this:

Cust1    Product1, Product3
Cust2    Product9
Cust3    Product1, Product2, Product3, Product4
Cust4    Product1, Product2

I've done this by embedding a call to a VB function from the next query in the nest, but even at this early stage of development I can tell the speed (lack of) is going to be an issue.

Is there a clever way to flatten as shown above, using just the Jet engine?

BTW, the 2 tables underlying Query1 are fully normalised and joined one-to-many  -  I am asking for a quick method to denormalise.

Stephen Bond
Otatara, NZ