Felix Griffin's Editor Mod
I had no idea it would get better after BEE Mod! 
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Single Player Tests - Excellent Partnership (Coop) - Single Player BEE Mod Tests
Thanks!
Now everything works except the SoT stuff and flip-flops. I think the rest is enough to release. Just don't use those two things.
Blender can export 3DS files directly; that's how I make them. The SMD tools for Blender can also import reference SMDs, so you could just convert them that way. (Remember to scale it down before exporting!)
So, portal 2 can use 3ds files?
Also, can't wait to start messing with the new elements on release! 
Aperture Science: We do our science asbestos we can!
RELEASED! Felix Griffin's Editor Mod (FGEMOD)
Known issues at the moment:
- Portal deflections cubes were acting up, so I removed their global_ents from the modified elevator instance. You can try adding them back in, although I don't know how well it'll work.
- Cameras...I don't even know. I set them up the same way I did everything else, and yet both the editor model and instance still rotate crazily in-game.
- Orange gel cubes are temporarily removed, using that won't drop anything. I needed to debug them.
- Non-lemon cubes won't make particles when ignited from a torch.
- Torches look just like buttons in the game, despite my attempts at using decals.
- For the sendificator to work, the mandatory observation room must be on the very edge of your map (or at least with no portal walls behind it), and on the same side as the entrance door starts out. This is due to a weird bug in rotation that I'm not sure still exists, but just to be safe...
- The player can't walk in a single 128x128 cube under a downward-pointing vactube entrance, because of the clip ramps I used to get you in. I'm still trying to figure out how to fix this one.
And some others, probably. Tell me how it works for you!
The FGEMOD Testing puzzle just contains a bunch of different things, I've been playing around in there whenever I add a new element. It's not a very good puzzle to see how things work, but you can look at it if you want. I'd recommend making your own simple test to start playing around with.
To make your own test elements for this, make an instance as you would normally for the editor, then make a .TEST file. This contains two lines of metadata (name, then description) followed by the Item block from editoritems.txt. Replace the palette position with $P so the mod will replace it, then put it in the Science directory.
Credits are in the individual .TEST files.
I'm trying to run your exe in scripts, but i get this error:
Hm. I thought I static-linked it. I'll add those files to the package.
The mod is impossible to use on a Mac (the .exe won't even run in WINE). Perhaps you could port the .exe?
I've been planning to release source so you can compile on Mac or Linux, but I think I hard-linked something wrong and my include directory contains another include directory, ad infinitum. If/when I fix that I'll give you the source. But at the moment all I can get is the preprocessed source, which will compile but is hell to edit. Sorry.