I use a kitchen scale. For the hanging items, I lay the long bottom of a clothes hanger across it with hook hanging under. Hit the Tare weight and pick it up from bottom of the scale. (I've also used a board ala diving board style to hold it).
And yes, I've weighed even empty plastic bottles to get the lightest one and their caps. It's a terrible affliction.
On a side note, I was training up to go Special Forces in the 90s. I was carrying a full Army ALICE Ruck of everything I could possibly get into that thing and walking it in the desert in El Paso every night and weekends 17-20 miles.
I would love to know how much that heavy pig weighed. It had to break 100 at least based on what I can remember in it and I only weighed around 140!