I'm in the midst of building for an adult male veiled and it will be 3' x 3' x 4' (WxDxH). and this will sit on a 20" base. He's small now so I still have time.
it took a day to build, and about 2-3 hours to secure everything, and place it. I wanted to mimic the best i could realistic habitat by giving a canopy/dense leaf population, and finally jungle floor with little to no light this allows for a 100% shut off to uvb/uva so he can photo regulate to his desire.
i wish they were all real, but only the 2 big plants are. im using a Zilla tropical 25 series 36in 25w in the back that im not sure you can see its a low profile strip light
oh and i use a 150w day blue to keep ambient temp up, and a 75 day white spot for him to bask under. keeps the cage between 78-85, and at night around 74~ with lights off (long as my door is closed other wise i would need to use the 100w black night bulb which far as i can tell just puts off heat i dont see any light)