1) I want to make sure I'm creating the bottomless pits right. I know to make a trigger_hurts and set it to 1000 and fall, but do I then encase the level with the texture black/toolsblack_noportal or is there a better way to do this?

2) I got an error that says, "numportals<numareaportals". I don't have any area portals either. Anyone have ideas as to what the problem is? (I exported it from PeTI if that matters, too.)

3) Well... This is more of a request. Does anyone want to make a map with me? I'd love the experience and I have a lot of puzzle I want to make into hammer maps.

The map I'm making mixes aesthetic themes. It has the destruction and largeness of the wheatley destroyed theme and the silence and overgrowth of the pre-GLaDOS chambers. This idea is something I have seen done before, and seem cool and unique to me. I though you could also mix the underground and reconstruction pretty easily and that you can mix almost any themes together that aren't clean.

Do you guys have thoughts on the questions or the idea of mixing aesthetic themes?

2) It sounds like there are a ton of visleaves there. Tie small brushes to func_detail.

3) The best way to learn is to make lots and lots of maps. Doing everything yourself will help with your weaknesses as well as your strengths.

@Portal Master:

1. If you don't really want to create a 3D skybox, which in the beginning could be more complex for you, i'd suggest you a 2D instead. It's far easier:

2. Texture all the desired walls of your pit with the toolsskybox texture

3. Go to the Map menu > Map Properties and there, write a skybox name from the available ones into the 'skybox' property. I'd suggest the sky_black one.

4. That error is not caused by visleaves, but because of your areaportals: an areaportal must have only 2 faces exposed (the other 2 use to be touching world brushes). Since you are a beginner I don't think that you dared to add any So my supposition is that there is a problem with one of the areaportals at the doors. I think that there are 4 of them if you exported a map from the PTI. So let me know:

5. since you exported your map and not decompiled it, your doors should be instances from Valve so there mustn't be a problem into it, but, did you collapse the door instances and play around with its different parts position? ...if you didn't...

6. did you orient any door differently from how you found them after exporting your map? if you turn them around a bit for example (in order to mess around with destruction theme), you might have left one of these areaportals faces that were touching a world brush exposed...

7. did you tied to func_brush or func_detail any of the brushes that are touching a door?

8. About this, I deeply suggest you to learn the hammer editor basics before continuing. I use to recommend SolarChronus video tutorials because they helped me a lot when I was learning and have good memories about them. And with regards to mixing aesthetics, I think overgronwn and wheatley themes can be mixed (not all of the styles can be mixed up altogether though) but you need to think about the coherence of every bit you place in, and maybe take your time to create a proper transition between chambers

I know a lot of the basics for making the chamber, and I'm pretty surprised I got as far as I got with it. I have looked at SolarChronus's tutorials before and they are very helpful.
My only problem with certain topics is that the information is out there, but it's sometimes scattered and hard to find.

Thanks for the help, it's really helping.

If you're new to hammer let me give you the best tip you can ever get: DON'T work on exported pti maps. They are a total, total mess. They are highly confusing in their logic and just not working properly.

Use your pti map as a inspiration source; but re-build all your brushwork from scratch. Learn how to use the various entities, and learn. Re-skinning/slightly adjusting pti levels is not going to teach you how the tools work.

Then for your bottomless pits; just make actual pits and as josepezdj suggested: use a 2d skybox.
I've seen a lot of experienced portal 2 players struggle with 3d-skyboxes, they are complicated and I would highly suggest not to use them until you feel confident with the engine and the tools.

Areaportals are automatically included in the door instances of the pti if I'm correct; if you messed up some brushwork there it might cause this error.

As for working together; what do you mean with that? I'd be happy to playtest beta versions and help you out if you run into any problems; feel free to add me on steam: Lpfreaky90. If you mean together working on one vmf, sorry not now

This is one of the best sites, you guys are so nice. (And professional) Thanks, this all helped so much.
@Lpfreaky90:
I meant make a map, but beta testing/helping would be great too. My steam name is Portal Master, and I'll add you.