I like Airlocks! I build them on my planet bases! I love to build so I will probably always make my own and I tend to make them large, like moon buggy size on some. I did make a "true" airlock and it worked well, I just got tired of waiting for it to cycle all the time so now they just "look" good. The logic and blocks are in game for you to make one now. Although some enhancements to some of the current blocks would make things much easier to build without having to use other mods or so much "vanilla" redstone, (like "falling clock" or inverting redstone signals). For instance, just having the Airlock Controller be able to open on redstone high or low would be a big one. Or being able to toggle redstone output from the O
2 detector. I believe these are scheduled for the power overhaul that is upcoming. Unfortunately we need more developers, and modelers that can pitch in.
There has been some discussion with Dev's about adding "hatches" and other "doors" and they are planning to. Hopefully when they get some time to start working on them we can have a thread on hatch types, like very low inertia doors, sounds simple but not so IRL, a door that can be pushed/pulled in 0g... ie controllable momentum that doesn't want to kill/crush you. I think the biggest issue is Dev time plus lack of Models and Textures. Adding a block to the game is more work than most people think. Some of the Dev's have mentioned that if they had "Good" models they would add them, so if you can make some models/textures
To make an Airlock, build a "chamber" with an airlock on each end, set the airlock controllers to open on redstone & player range. Add an Oxygen Detector and split the output, send one directly from the detector to the "base" side airlock controller, on the other, invert it and send it to the vacuum side airlock controller, then use an Oxygen Sealer(or 2) or a Bubble Gen(be sure the O
2 Detector is in bubble). Then flip a lever, wait for O
2 pressurization/cycle. If you want to have outer airlock to unlock for multiplayer you have to make a remote "4 way" switch to toggle the gen/sealer on/off. You could use logic gates(my preference when available). You could also use pistons, but I don't like the noise or bulk of using them. You could always just use the illusion of an airlock, by having the them far enough apart so they can never open at the same time, and use "falling clocks" on redstone to force a delay in redstone signal to airlock open event to account for or simulate cycle time.
Here's an old version on one:
https://imgur.com/U0WDypO
I really like the blocks themselves too, and use them as doors on the overworld since I like to make big 3x3's. And who doesn't like star trek doors!!?