For the glass, you can use a thick acrylic or plexiglass (pretty much the same thing with different names). Home Depot or the similar may not carry glass in the size you need, so you may need to go to a more specialized store. As for the height in the cage, it may not be easy to have a tall one. The great thing about tall cages is that they hold humidity very well. The bad part is that they require more heating equipment to heat up the added volume which may not even be necessary for a large retic (I doubt that he climbs). You want a cage that has substantial height of course, so build a cage that has the right ground requirements (9'x5' when added gets you 14', fine for your retic) and have the height be what is aesthetically pleasing to you. I would say that 6' tall looks good. Just use spot incandescents. Day and night. I know that a lot of brands sell day spot bulbs (even the ones at Home Depot are fine), but I only know of ESU Reptile having night spot incandescents in blue, which is what I favor. You could buy Zoo Med or Exo-Terra infrared spot bulbs though and have them on all day and night what ever you prefer. Buy a few bulbs and hoods if necessary.