290 is a ceramic insulator
291 is an eraser shield. Besides drafting, is was used for typing--in the days before whiteout and deletion paper.
293 looks like a collectible piece of barbed wire
295 is a corrugated fastener--they were driven into the end grain of wooden boards to hold them together. A very common use was on the end boards of wooden produce boxes. These used to be called by a politically incorrect, offensive name
One you had recently, that I no longer see--an iron meteorite. I ran across one for sale at a flea market last weekend.