I watched a video a while ago where someone attempted exactly that. It’s probably more elaborate than you’re looking for, but the results are pretty great and maybe you can get some inspiration.
Building a realistic artificial sun (for dark winter days)
In this video we'll be building an artificial SUN! Also, check out http://KiwiCo.com/DIYPerks50 for 50% off your first month of any subscription over at Kiwi...