Thanks Brillwill, this is really helpful. I keep looking at mine and thinking I might have luck creating a vertical opening along the right edge of the record side -- to create a side opening. That way the cut wouldn't risk growing (with use) into the cover art side. Hmmm. I'll let you all know how it goes after I work up the nerve.
I'm also trying to figure out how I want to open this thing. A facebook commenter mentioned that, when he cut the vinyl side, the string side lost it's vacuum seal. Has anybody else experienced this? It'd be a shame to have to ruin the cover art in order to listen to the record.