Here some of my attemps at making a Longwave UV Display and some commerically available options.
DIY 50 Watt Longwave Light Bar - So far this has been my best result. Requires a little skill but not too bad. This one lights an are 34 x 12 x 14 inches (because that was the book self I made it for) but I believe it could do 40 x 24 x 24 inches. Cost is less than $150 US dollars.