I’ve done quite a bit of potting/ encapsulating in developing dive computer prototypes and other underwater electronics. Are you encapsulating electronics, and are any of those small SMT parts? If so I would be cautious about anything that sets up very firmly, thermal expansion can break PCB bonds down the road. It may be best to use a very soft compound like Dow Sylgard if that’s the case. I have found Smooth-On to be a good source for small amounts of urethane and epoxy resins of various types.
I had some success potting parts under pressure to reduce bubbles, putting them in a common painter’s pressure pot after pouring the potting compound.
Since our prototypes need to fly as well as go underwater, are exposed to ambient pressure, and we were using soft potting to preserve PCB bonds, what I eventually came to was the realization that I would never get our parts sufficiently bubble free without doing it under vacuum, even with very low viscosity resins. Unfortunately this needs a really good vacuum to be effective, I was able to get a high vacuum used lab pump on EBay reasonably, and make a chamber out of stainless restaurant containers. That’s made the process a lot easier.