Method:
PORTALED up to SECOND LEVEL, grabbed TURRET, which was just in reach;
Noticed LIGHT BRIDGE, walked UNDER it and toward FAR WALL, grabbed TURRET, then obtained FIRST LASER CUBE;

FINAL AREA was more complex:
Kept a LASER IN and LASER OUT portal and positioned SECOND LASER CUBE just so that LASER OUT on FAR WALL would activate LASER TARGET; traveled to SECOND LEVEL [see above], then was barely able to jump and shoot FAR WALL.

Pros:
• Elaborate design;
• Felt clever solving it;

Cons:
• Not sure if my solution was the intented one; (Method to follow)

Now you can just grab the last turret

that is correct besides the last part. You need to in some way kill the turret

Not sure I solved this correctly. Fling bounce to first turret, threw it over, got the cube (never used the flip panel here, though I activated it). Moved to second turret, lased it, got the 2nd cube. Used the 2nd cube in line to redirect laser directly to catcher while first cube was using portals to hit the catcher. Walked out, portaled the bridge, made a portal to the extreme left portalable panel from bridge, walked over dropped to exit area, ran out before turret could shoot me. I also discovered that you can laser the 3rd turret as well, though it's not necessary. Good puzzle. Difficulty 5/10 Design 6/10

Wow, thank you for all your comments. Thank you Donderbus for posteding those images that really helped a lot. For the most part that was how it was supposed to be solved, so that's very good. Thanks again, I will try to fix that laser field so it isn't as easy to bump in to it.

Anyway, I really liked this puzzle. I think this is my new favourite. I was about to give up, but then I solved the first turret.

There's a bit of an annoying execution puzzle with the laserfield in front of the pointlessly portalable wall. I died a few times trying to swap the cubes .

I didn't use the flip panel, and the panel under the water was only used as misdirection to trick me, and I didn't kill any turrets with the laser. It still used 3 different ways to kill or get past the turrets though.

I did the same, except I couldn't work out a way of killing the last turret, so I just used the cube as a shield and walked past. (It's also possible to get past with no shield).

This is what i did:
http://postimage.org/image/6y73tvk3n/full/

would you mind writing down what you did step by step so I know you didn't find an unitentional way to solve. Thanks for testing

You don't have acces to a laser at start so I don't know what you meant in the discription.
Nice test.