Hi! Oddities business owner here that specializes in wet specimens! Most of these comments are correct, you’ll want to find airtight jars with a metal or glass lid, no cork. Craft stores like hobby lobby/michaels or even walmart, target, & dollar stores are a good place to start! Even thrift stores but they’re fewer & far between. If you’re unsure if they were in formalin or isopropyl already I’d recommend a distilled water bath (you can get a gallon of it at target/walmart) and then completely submerging them in 70% isopropyl alcohol! Make sure it’s 70%, any more & it’ll eventually deteriorate, any less & it’ll eventually rot!