Nice puzzle! The intended solution has a neat ending. Thankfully I checked the comments before becoming yet another shortcut-informer.

Nice, I like a challenging game, and just right size chambers myself; though here is a player trap and I am not so sure I play intended unless the panel with Square Sign is really meant as Red Herring:

1. Get the Red Reflective and Franken, order is irrelevant.
2. Funnel is running interference. Get it off
3. Fling and get Red to burn off the 3 turrets. Have it back to Funnel Polarity when you are done, put it to be sidelined.
4. Franken sits at the X sign to clear the pink field.
5. Go by funnel to the Entrance, go to that statue pedestal thing, sideline the Polarity button with the funnel.
6. Get up to Exit and drop Blue, do what East Berliner did; over the wall.
7. Almost done, no Cube Swapping, same play but now with Blue hitting the Exit trigger, repeat, solved.

it may not have said you were a playtester. you were thanked for your help. i will follow you so i can see when your new work comes out. i will keep an eye out for Salt Mines. i just finished portal reloaded. cool concept.

@jandlml I saw your other comments on my workshop, I'm glad you enjoyed the maps! I don't know why I was listed as a playtester for Underground , the only thing I contributed to that map is help on how to use the BEE2 vactubes correctly.
I think I really need to fix this puzzle now, the unintended solution seems obvious enough that basically every comment tells me about it. I'm just working on so many projects at the moment that I don't really have time to fix this old puzzle, and the map editor file is also not on my new computer, so that complicates it further.
In case you're curious why I'm that inactive lately, it's because all my good puzzles are used for the upcoming Portal mod Aperture: Salt Mines ( discord invite if you're interested [discord.com]) I work for as a puzzle designer. Plus, my biggest project for my own workshop is being worked on at the moment, so you can look forward to that.

i saw your name as a play tester for Underground. i am always looking for new maps so i decided to give your maps a try. this was a fun map but im not sure i got your intended solution. i also played Duality another fun map. for some reason i couldnt leave a comment on that maps page.

That was fun, especially the ending.

I keep not getting around to update this one, so many comments that I need to fix it. I just don't have time at the moment. Thanks for the video though!

As promised: unintended solution.

What great fun; not sure if I completed the last chamber as you intended, but I really enjoyed it, so who cares, definite thumbs up. I'll replay tomorrow, make a walkthrough video and then watch what others did.

Thanks for the reminder that I really need to update this one. Several people by now have figured out shortcuts, and I keep forgetting to update it nonetheless. Glad you still liked it!

I enjoyed it. Here's my blind run. https://www.youtube.com/watch?v=4UJPwmU144w A little before the halfway point (~9:35) in the video I do an easy shortcut that allowed me to to promptly exit at that point. Although it is a fully legit move, I figured it wasn't intended because at that point I had not ever spawned the blue reflective cube. I went back and finished what I figured was the intended solution.

@SpielSatzFail Thanks! I'll take a look later and probably add it to the description.

Sorry for being late, I was lazy :-( Here we go: https://youtu.be/hskGTAhpa88
Please note that I'm not the one who's actively looking for exploits, softlocks etc.; I only mention them if they are obvious (obvious enough for me). I'm sure this is the intended solution.
You can link the video as a walkthrough if you like (btw it is set to "not listed" and can only be accessed with a link).
I tried to play it smoothly. It may not be the fastest playthrough, but I want to keep it comprehensible.

@SpielSatzFail So, onwards with "feedback for your feedback"
Really glad you liked this one, I would say it is the best of my public stuff to date.
I am aware of the trapping situation you showed in your screenshot, and even noticed it shortly after publishing. If you were to take a look at Narkodes' video below, they found a lot more exploits with this map, which I am really glad you didn't. Honestly, you commenting on my maps just shows how bad I am with making remakes in time...
Thanks for pointing out that I forgot to link the Demon Arisen map that inspired this, I will update the description shortly.
Since this one already has some reported issues, a walkthrough would be nice to see if I need to change something else, but only if you don't mind going through the effort of recording and uploading one.
Thanks for your criticism and feedback, I really appreciate it!

Great one! Very satisfying sequences. For now I only have a screenshot showing a possible softlock situation: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2238036486
Nonetheless a thumbs up :-) ...even though I'd expect you not only to mention demon arisen but also to link the exact corresponding map that was your inspiration.
If you like I can provide a walkthrough video, since this map is a little sophisticated ^^

Nice puzzle.

@Narkodes Sadly, no. You essentially skipped the two core moves of the puzzle by both using the other portal surface back in the room with the two buttons and because of that also not using the other laser receiver. I'll see when I find time to fix it. Thanks for showing me!

https://youtu.be/ZGB_UQXob6o (still uploading)
Is that your intended solution?

nice