“The Vital Apparatus Vent will deliver...”
~ GLaDOS

This is a somewhat more advanced guide about Aperture's Vital Apparatus Vents for gels and cubes, and so it may be bypassed without loss of continuity, just as some test chambers are sometimes bypassed in the same way. That being said, they are rather important apparatuses, and as such I will at least show you somewhere to begin.

If you're lazy and don't really have the time to make your own instance of a cube dropper, you can go with one of Valve's instances that they used in their maps. They are located in the maps\instances\gameplay directory:

• cube_dropper_shared.vmf: this is the core instance for the cube dropper, containing all the logic stuff necessary for it to work.
  
• cube_dropper_monster_box.vmf: used to drop frankencubes instead of normal cubes. May be buggy.
  
• reflectocube_dropper_*.vmf: used for redirection cubes instead of normal cubes.
  
• sphere_dropper_*.vmf: used for edgless safety cubes instead of normal cubes.

NB there are also "dirty" versions of the above (except for spheres) for decayed- and reconstructing-themed maps.
Also, be aware that some of Valve's instances were made for special, one-time, in-game scenes or were leftovers from the development stages, and may be buggy.

To control them:

• To drop a cube at the touch of a button, trigger the $trigger_to_drop_box or @cube_dropper entity inside the instance.
  
• To enable auto-respawn, use a logic_auto and set it to enable the @cube_dropper_autorespawn entity inside the instance.
  
• If you want your cubes to spawn the first time, you'll also need a logic_auto (or a trigger_once by the entrance). Simply set it to drop a cube once.

I also recommend tweaking these instances to fit your needs if needed. Just be sure to save in a separate file.

I myself have spent a fair bit of time wondering how many bare entities it would take to make a perfectly working cube dropper, and I think I've come to a rather definite conclusion on the number: 7. The rest is just details. At the core, we have:

• A prop_dynamic which will be the dropper model
  
• A point_template
  
• An env_entity_maker to continually spawn cubes for each time one gets lost
  
• A prop_weighted_cube or prop_monster_box, 'cause we all love our companion cubes!
  
• A logic_auto
  
• A trigger_multiple, set to filter out only cubes (use a filter_activator_class to do the job)

Everything except the point_template and the logic_auto will need a name. To begin, in the env_entity_maker, set its "Point_template To Spawn" keyvalue to your point_template, and in your point_template, set under "Template 1" the name of your cube.

For the "details" part, we have:

• A button or other activator unless your cube is going to have some sort of auto-respawn
  
• Clipping brushes (useful if your dropper is near the floor)
  
• Lighting to match the dropper skin changes (see Valve's redirection cube instances for a good way to do it)

To set this up, you'll need to place all the entities accordingly:



Next, you'll need to set up the I/O:





...and there you have it, a cube dropper you can be proud of.

To simulate the "auto-drop first cube" behavior, have a trigger_once (positioned in an area either near the start of the chamber or when the player enters the room with the dropper) in place of the first button press.

To enable/disable auto-respawn, just add/remove the output coming from the cube.

One thing to be wary of with all cube droppers is if you're not using the normal pedestal button (prop_button) for an input device. In that case you can use an additional logic_relay to gate your input to 3-second intervals (assuming auto-respawn is off), so as to prevent spamming from ruining everything:

For this, you'll need a cube and a cube dropper of the same type (see above...).

If you don't have auto-respawn on and have a button for the dropper:
1) Create your cube and give it a name.
2) Create your button and set it to drop a cube when pressed.
3) Set up an additional output for the button: to fizzle (dissolve) your pre-placed cube when pressed.

If you have auto-respawn on and no button for the dropper:
1) Create your cube and set it to drop a cube.
2) That's it!

The advantage that this has is that now you can (for example) place a cube up high on a ledge but have the dropper in the middle of the room so that the player doesn't have to go through the tedium of retrieving the cube again. You might also use it to bring the cube a bit closer to the players when they enter an area while leaving the dropper a bit further away.

These are, perhaps surprisingly, easier to make than the gated cube droppers that we've seen a bazillion times.

To do it, you'll need:

• Some prop_statics for the pneumatic diversity vent used to deliver the cube
  
• Optionally, some trigger_pushes to move the cube out of its spawn position and into the testing area
  
• A trigger_multiple with a filter_activator_class on it, set for prop_weighted_cube
  
• A logic_relay
  
• A prop_weighted_cube (or prop_monster_box), a point_template, and an env_entity_maker

Name everything except the props and trigger, and then as before, in the env_entity_maker, set its "Point_template To Spawn" keyvalue to your point_template, and in your point_template, set under "Template 1" the name of your cube.



If you don't have auto-respawn on and have a button for the dropper:



If you have auto-respawn on:

Interestingly, all gel isn't always dispensed in the same way. Sometimes it's a flow, and other times it's a great, big ball of gel. We'll soon see how to create the former, but the latter requires another entity: prop_paint_bomb. In either case, you can set the type of gel you want to use.

While the open droppers aren't really used for cubes, they are used for those big "paint bombs" that have been cutely exploited for their ability to bounce off of faith plates. The creation process is almost the same as for open droppers with auto-respawn, but since the droppers can continually be dropping gel bombs, you'll need a logic_relay to control the gel flow if you have an input device for it. Here are the details:

You'll need:

• Some prop_statics for the pipe(s) used to deliver the gel
  
• A logic_relay
  
• A prop_paint_bomb, a point_template, and an env_entity_maker
  
• Depending in your input device, a second logic_relay

Name everything except the props, and then as before, in the env_entity_maker, set its "Point_template To Spawn" keyvalue to your point_template, and in your point_template, set under "Template 1" the name of your prop_paint_bomb.



The setup is identical to open droppers. However the I/O is a little different.

If you don't have an input device and just want the gel to keep on flowing, as I said before, you don't even need the logic_relay. All you need to do is to set your prop_paint_bomb (via the OnExploded, NOT the OnFizzled, output) to spawn a new one (using the env_entity maker's ForceSpawn input) after half a second.

If you have a pedestal button (perhaps with a ticking timer on it):




As with cube droppers, the I/O is a little different when any other input device is involved. In that case, you'll need a second logic_relay and these I/O for everything:





This will prevent spammers from wreaking havoc on your gel dropper(s).

• I really can't think of many mistakes other than to use too many entities in a cube or gel dropper.
  
• Forgetting to debug droppers might be one mistake, but overall...
  
• Droppers aren't always common in Hammer maps on the workshop, so I can't seem to find many mistakes for this guide.
  
• And that's good, isn't it?

More information from the VDC Wiki:

• The Aperture Science Weighted Storage Cube
  
• The Aperture Science Vital Apparatus Vent (a.k.a. "Dropper")
  
• env_entity_maker: this is the key entity that makes all droppers work. If you get lost when analyzing a dropper, remember this entity.
  
• The prop_monster_box entity
  
• The prop_paint_bomb entity
  
• The prop_weighted_cube entity

Please note that there are still some works in progress. This section will be updated as I finish more guides for you!

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Please feel free to leave a well-reasoned question or comment below. Either I or a qualified Test Chamber Associate (you'll know because they make all the good maps on the workshop) will respond. If your question or comment is not well-reasoned, I recommend reading over my guides again until you understand them 100%. No further information is required here or will be provided, and you will become an excellent Test Chamber Designer — using Hammer!