Rulers; When I brake one or the markings wear off
Cutting Mats; only if they warp
Rotary cutters; still have my first one, works great
Rotary blades; When they start to skip
Pins; when I run out of them. If my pins become dull, bent, or rusty I get rid of them
Needles; hand and machine get replaced as they get dull
Chairs; have only had 2 first was a dinning room chair, second I have now, got it when I moved into my sewing/craft room
Sewing Machines; get new one only after the one I am using dies
Scissors; replace after someone uses them for cutting something like sandpaper, wire.....
Seam Rippers; again replace when they get dull
Because I live so far from a fabric shop I do have stash of notions. I keep 2-3 of everything on hand just in case