Flatsrat,
All great advice, I've tried it all to make good pours with these molds. I vent just a little differently. Instead of placing objects between the halves, I slightly enlarge the channel that the hook shank sits in. This allows the air to escape without any flashing on the body of the lure. You may get a little sliver of lead along the hook shank, but it is removed quite easily if you remove it at all.