Anyway it's funny that it came up right when I was working on my very first resin project, preserving something from our most recent California trip. Our flight back from Palm Springs to Paine Field in Everett (PSP to PAE) was Alaska Airline's inaugural run, and they gave us cookies with the airport codes on them, as well as pins.
I'd read about some items needing a layer of protection before putting them in resin so they wouldn't melt, and thankfully I had two cookies because the first suggestion I tried, Mod Podge, ruined the first one. I used a spray on the second one and it was fine.
I learned several more tips for getting rid of bubbles so hopefully future casts will be clearer. I was surprised to see how bubbly this one was, though. It looked a lot clearer in the mold. I guess because it's white. It should be sanded, too, but I'd like to practice sanding on something else first so I know it won't get ruined.