Would this be a good technique if you can't get a seporatory funnel or a glass gravy/fat separator? From what I understand the vinegar will freeze while the d-limonene will not, making separation a piece of cake. But is this likely to cause problems in the yield/potency (aside from the extra evaporation time)?

The other thought I had was using a bottle like this:

to separate vinegar and d-limonene. Left upside down and then the nozzle opened to let the vinegar seep out... Perhaps a hole in the other end to avoid air bubbles as it pours out? These bottles are recyclable so they can't be the type of plastic d-limonene would dissolve, right? There's no plastic type stated on this sort of bottle. I'm aware of the traditional Glad-bag DIY solution to separating, but those are difficult to handle in my experience. Thanks for any tips.

Vinegar freezes at about 28°F while limonene at -102°F so yes it'd work. However if you use a little excess vinegar and some patience, you'd separate layers while they're still liquid. Also glass would be preferred since nobody knows which plastis is that bottle made of and even if it won't melt in your hands it may still leach unwanted polymer molecules in your extract, so you'd better use glass.

Drilling a hole on the side would avoid bubbles, but sincerely if you're going to freeze vinegar I don't see a need for that bottle to separate it from limonene, just take the frozen layer and set aside.