The California Air Tools style pots that are already set up for resin casting are generally the best option if you can afford the higher cost. Basically the ones that look like this or this. Similar style pots from other brands should also be fine although the only one I've actually tried is the CAT one. Other styles of pressure pot will be cheaper but are also going to require some amount of modification.

Note that the pots that have a thin plastic lid like this are NOT pressure pots. Those are vacuum chambers which can also be useful for some resin casting purposes but they aren't interchangeable with pressure pots. Vacuum chambers are typically best for projects that are too large to fit in a pressure pot.

I bought the California Air Tools 2.5 Pressure pot for resin casting! it came all ready to go, other than adjusting the regulator. Here is a link

https://www.amazon.com/dp/B09T3YTG5Q?psc=1&ref=ppx\_yo2ov\_dt\_b\_product\_details