How to keep a record of which toys a customer had in the past?
You can use a Look Up field in the Customers table. Use it to look up the Products field on the Orders table. That will give you a field full of linked records to the products that the customer has historically ordered.
How to get a suggestion from Airtable which toy to give based on age of the kid, past toys sent and in stock toys. We know the age of the kids so I guess we can just give every toy an age range and when the kids is within this range it would be shown?
This is a fairly tricky problem I think. It will require some clever combination of Formulae, Look Ups and Linked Records.
What would be the best way to keep track of the inventory of a toy?
We would have multiple units of the same toy. How can we keep track of how many times a particular unit has been “rented out”.
It seems like you should probably have an Units table as well then. The structure would then be that Orders are linked to Units, and Units are linked to Products (and Orders are still linked to Customers as well). You can then Roll Up the Orders in the Units table to count how many orders are linked to that unit.
Under this structure, all product specific information is entered into the Products table (price, age range, etc.)
All unit specific information is stored in the Units table (specific unit code, build date etc.). If you need product specific information in this table you should Look Up from the Products table.
In the Orders table you can Look Up the Products Linked Record field via the Units table. Crucially, you should not link the Orders table to the Products field directly; only link them via Units table. Maintaining this proper database structure can help save you from future problems.