A word for “useful components”?

Solution 1:

I'm a bit hesitant to put forward toolkit as it does not really capture things like scraps of cloth. Still, may be of use.

1 A set of tools, especially one kept in a bag or box and used for a particular purpose.

1.1 Computing A set of software tools.

1.2 A personal set of resources, abilities, or skills:
intuition developed from past stock market experience becomes a vital part of an investor’s toolkit

Solution 2:

This is more suitable for computing than sewing, but consider utilities, which (as noted in the link below) is derived from utilis (useful).

Please excuse the self-referential definition.

Utility noun 3 Computing A utility program: a handy utility for converting one graphics file type to another - ODO

Your sample sentences would then be:

• Don’t forget to bring the needed utilities with you” (addressing to a service engineer); and
• “I put all my utilities into this folder on Google Drive”.

Solution 3:

I can think of only one noun that fits here nicely:

Don’t forget to bring the (adjective, if needed) essentials with you.

You may want to put an appropriate adjective before the word i.e. "programming essentials"

-Essential

a basic, indispensable, or necessary element; chief point: