LED Heatsink solutions

Regarding the heat sink, can you use an aluminum plate with fins on the back?  Something like this one from Aavid might fit but Wakefield and other extruders will make them too and different companies have different minimum order amounts.  http://www.aavidthermalloy.com/cgi-bin/exdisp.pl?Pnum=61585&LengthUnits=in&ExLength=3&airflow=57.2&CType=Natural&AirUnits=LFM  I don't know enough to be able about your application to guess if this will work but you need a heatsink with more surface area and access to air outside the light box.

I don't have to deal with such tight space constraints so I am just guessing but iIs it possible to direct an air flow toward the heat sink?  I know of some applications where space constraints forced a developer to use a copper heat sink but I've never had to do that.  There are also some graphite products that could be interesting.  Or could you turn the problem around and generate the light somewhere else where you had more room and then pipe the light into the box?

Fibre optics, light pipes such as the ones made by 3M, light tubes (see Wikipedia), etc. are all possibilities.  I think you'll have to be creative, but maybe you can borrow some ideas that you get from researching daylighting or the process of getting light into MRI rooms in hospitals.  This is not a problem I have had to solve so I really don't have any detailed solution for you, but it sounds like a fun project.  Good luck with it and perhaps someone more knowledgable can offer some better advice.