Advice on custom data types

In my initial database schema I have certain relational tables that could strongly be thought of as objects. As an example one table might hold a bunch of related points(x,y,z) where the rows could be grouped by a foreign key to another table. Anotherwords each set of points belongs to one row in another table.

So from what I have been reading here in the forums its usually best to avoid custom data types, but I would not be querying on the fields contained in the possible objects, nor would I be indexing on them. It would essentially just be storing them and extracting them as needed. Would this be a good case for a custom data type, written as a C struct?