If one was building a light meter themselves it might then be worth seeing if they could get some pieces of narrowband filter glass (or just a piece of your favourite filter) and get multiple readings out of it at the same time. Or add a switch and some duplication and you can get whole scene, spot and center-weighted metering. That is, if its fun and you want more than just a light level reading or want something special.

or, of course you can make a matrix meter with cmos sensor colour metering... digikey carries all you might need - or possibly more than enough to damn your soul :-P