272. Some kind of clamp, but I don't know what for.

273. Lathe dog.

274. Pinstripe painter. Fill the bottle with paint, invert it, and roll
paint on with the wheel. If not for paint, then some other liquid, maybe
adhesive.

275. Thing for throwing clay pigeons when shooting skeet. (Save the
poor, defenseless skeets! ;-)

276. Camera iris.

277. Tee-nut for wood or particle board.

Now, I'll go read the other answers on rec.crafts.metalworking...

-Ron