To list the set $U$ using the roster method, we include all the unique elements mentioned:

$U = \{3, 16, 20, 29, 32, 44, 48\}$

This is a set of numbers written in increasing order, with all elements listed once.

Would you like further details or have any questions about this?

Here are five related questions to expand on this topic:

1. How is the roster method different from the set-builder method?
2. What are the properties of a set in terms of uniqueness and order of elements?
3. Can sets contain duplicate values, or are they always unique?
4. How can we define a set of all even numbers between two given values?
5. What is the cardinality (size) of the set $U$?

Tip: When using the roster method, always make sure to remove any duplicates and arrange elements in a logical order, usually increasing.