A very small puzzle I made, it took me some time to make it.
Kinda complex... But that only depends in how good solving puzzles you are.

v0.92: Fixed cubemaps and added hints in the txt file.

File Name: sp_zro_1cube.zip
File Size: 2.32 MiB
Click here to download sp_zro_1cube

Looks simple but has some cosmetic imperfections like the lack of cubemaps(type 'buildcubemaps' in console) and these weird overlapping wall lights.

My solution to getting the only puzzle seemed like a alternative/unintended one so I can't really judge about the difficulty.
First I put the cube in the white wall opposing the funnel using the upper panel in the 'jump down' room(pic), then got the cube high enough to get in the funnel by simply placing a (lower) portal next to it(pic), quickly placed that portal opposing the button and made the jump.

I'm playing custom maps and record my first time of playing them. So the run is not perfect and may not use only intended ways, but maybe it can let you see how other people may understand the map or you could just enjoy someone playing this map for entertainment.
Anyways, here is the recording:

-HezaIN53iY
(Link: http://www.youtube.com/watch?v=-HezaIN53iY)

Also note the video description for more feedback and my signature for additional project information.