Generalized Retailers - Retailers (online, local, & second-hand) that are do not specialize in any particular aspect (ie: big box retailers)
Specialized Retailers - These retailers have a well defined specialty, or best known for a specific category of product. Most of these will be online, however there are a few local options as well.
Software Options - Different software packages that can be useful in making things.
YouTube Channels - Different Youtube Channels which feature interesting or creative projects.