302. Looks like a tool to help stretch fabric when upholstering furniture
or car interiors.

303. It's a Dietzgen No. 6869 thingy that you look through to see stuff
;-) (Seriously, I have no clue)

304. Some kind of fastener, like a big staple?

305. No clue.

306. A gold ring.

307. A trammel point, it clamps to a bar. Usually used in pairs for
measuring and marking material (wood, metal, whatever).