Addons:

*The big three in this course are Hard Ops, Boxcutter, and Decal Machine. The rest are not needed, but recommended. Machin3 tools and Mira tools are great ones and are both free.

Hardops / Boxcutter / Hardops Inserts for Kitops (free):
https://gumroad.com/a/389477491

Decal Machine / Mesh Machine / Machine Tools (free)
https://gumroad.com/a/766964851

Kitops 2 (you could try Kitops 2 standard version which is free)
https://gumroad.com/a/779940979

Power Save (free)
https://gumroad.com/l/powersave

Mira Tools:
https://github.com/mifth/mifthtools/wiki/Mira-Tools

Cablerator
https://gumroad.com/a/341111923

Photographer 3 (this one is paid but Photographer 2 is free)
https://gumroad.com/chafouin

Quad Remesher (very expensive and not super useful for hard surface, I use it occasionally, but if you sculpt, this is a no brainer)
https://exoside.com/quadremesher/




Composite image:
https://unsplash.com/photos/pZ-XFIrJMtE

Photoshop plugins:

Pixelsquid
https://www.pixelsquid.com/

NIK software (mainly color fx pro and viveza)
https://nikcollection.dxo.com/

Infinite Color
https://www.infinitecolorpanel.com/buy-now

Knoll Sofwtare 
no longer available, but you could use https://www.compositenation.com/plugins/oniric?fbclid=IwAR2pepZhWLriaDS5Ed3i2tz4iTTm3OwXuWSP3oDhrE1tgqBq7tTdtvyE3ho


I recommend using a pen tablet for compositing
I use wacom pro, but any tablet will do