Recently made another viewing light for a friend with the same parts I made my own a year or so ago. A recycling shop provided the two lamp houses of a ceiling armature, I bought two GU 5.3 sockets, two Osram Decostar 51 50 watt 12V Cool Blue halogen lamps, in my spare parts archive were two 60 Watt 12 volt transformers and frosted clear PET foil 175 micron for diffusion The output drops just below 4000 Kelvin, continuous spectrum. It stands besides the monitor and shines on a magnetic white board. In the EU the Osram lamps can still be bought I think given several ads, I bought about 20 lamps five years ago, they are cheap. To get 4500 output you will need a somewhat higher transformer voltage, possibly more than 60 watt too. 4000 Kelvin is fine for me and I have two Normlight 5000 K viewing lights too.
The picture has another DIY project too, a data transfer cable + mounts/adapters between a Sigma EF 50 mm macro reversed mounted on a Canon FD bellows with an FD>EF adapter to a Canon 5D MK II. For the lens diaphr. control, Sigma set on manual focus. The concept will drive focusing too if the Sigma is used in its normal position but there are better ideas to start from.
Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htmDecember 2014 update, 700+ inkjet media white spectral plots