If I want to make my own drop in strut like Monroe makes for the rear, what parts exactly will I need to make it just like the "drop-in strut"

P.S. I realize you can reuse springs and probably the boots but I'd rather just get all new struts so I don't have to worry about anything going bad on it...

I just don't know what is all in one of these drop-in's.

Any info would be highly appreciated! My car knowledge is a slight hobby so I'm mechanic. I apologize for stupid questions in advance!
Thanks, AJ