Something I’ve picked up along the way that I thought I’d share.  I know a lot of recipes say to “firmly pack” curd into your mold.  I’d like to emphasize that.  Nearly all mechanical holes can be prevented by packing the mold very, very firmly.  I use my fist to press it as tightly as possible.  It may take several minutes to get it right; but it’s time well spent.  Even cheeses that press with quite light weight can be aesthetically improved by doing so; and cheddar knits quite well.