It is easiest to build this in creative.
Layer 1: You basically just make a plus sign on the ground made of 5 cobblestone blocks. Place a gold block in each corner (four blocks of gold).
Layer 2: Place a cobblestone block on top of each gold block (four blocks of cobblestone) and a nether reactor in the middle.
Layer 3: Finally, make another plus sign out of 5 cobblestone on top of everything, in the middle.
Place a chest nearby (to put everything into) and then change to survival. You might want to set it to peaceful if you don't want to be overloaded with zombie pigmen. Just tap the nether reactor (this only works in SURVIVAL) and a giant netherrack castle will appear around you. There will also be a heap of supplies that will spew out.
Collect these, dig your way out, and put them in your chest. This is one way to get quartz with out going to the nether. The castle will soon get a heap of holes in it. Switch back to creative, fill in the holes, decorate, go back to Survival, so you have a great tower to live in and helpful supplies to use!