OBSIDIAN TOWER
Screenshots: 6Timespan: September 2012  February 2013Versions: 1.3  1.4.7
Paul Soares Jr. has his Cosy Cottage to live in, and his Tower Of Power to brew potions and cast spells in. You can see them being built, and make your own copy, should you want to. However, I'm not about to let him have all the glory, and so I present... in glorious OpenOffice Calcovision (and via the magic of the PDF converter), the plans for one of my equivalents!
And now that you've seen the Creative preview, what if you want to go about building one for yourself? Are you so bored you're prepared to spend all that time mining all that obsidian? First of all...
Here are the plans (four page PDF)  requires 17×17 m²
You will need:  96 blocks of dirt (already in the ground)
 344 blocks of cobblestone (5 stacks + 24)
 2,666 blocks of obsidian (41 stacks + 42)  which I've worked out would take almost eight hours to mine, and that's just the hittingtheblocks process, not including transport time, making new picks, flooding new lava lakes, etc... so I recommend you obtain an enchanted pickaxe, preferably Unbreaking III and Efficiency V!
 1 door (iron, in this case, so it needed a button outside and a pressure plate inside)
 8 blocks of glowstone, which I hadn't thought were needed originally, but are if you want to keep monsters out
 1,055 blocks of wool (16 stacks + 31)  of which, in my tower, 110 are blue (making the floor numbers in the wool carpets) and the remaining 945 are purple. To dye this wool from scratch would take a massive 237 (pre1.7) roses and 583 pieces of lapis lazuli! But, if you've been mining for long enough, you should already have that  and you can always predye your sheep and shear the coloured wool off them.
 172 glass blocks (2 stacks + 44)  not panes!  hence, 172 blocks of sand to be fired.
 72 torches (1 stack + 8)  should have a ready supply of these anyway. To make these without any coal, you'll need 23 logs. Saw one into four planks; saw two of these planks into sticks (22 logs, 2 planks, 4 sticks). Use two sticks to smelt one log into charcoal, and the two planks to smelt three further logs. (4 charcoal, 18 logs, 2 sticks). Two of these charcoal will now smelt 16 of the logs into charcoal for a total of 18 (18 charcoal, 2 logs, 2 sticks). Saw the logs into 8 planks, saw the planks into 16 sticks, bingo. 18 sticks, 18 charcoal, makes 72 torches.
 60 Nether brick fence
 70 Nether brick stairs
 164 mineral blocks (2 stacks + 36) of emerald, diamond, gold or iron  which requires 1,476 (or 23 stacks + 4) of each individual gem or ingot!
 1 beacon, which can be anything until the requisite Wither is dispatched! Bear in mind it requires 5 glass blocks, 3 obsidian, and that elusive Nether star.
Now... let us approach building this same tower out of Nether brick in 1.5, and see how much Netherrack we will need, how much smelting it will require, and how many pickaxes it will use.
70 Nether brick stairs are derived from Nether brick in a 6:4 ratio; 72 stairs (with two left over) require 108 Nether brick to build.
60 Nether brick fence are derived from Nether brick in a 6:6 ratio, hence we require another 60 Nether brick with no waste.
And then, substituting the obsidian with Nether brick, we require a massive 2,666 brick blocks  for a total of 2,834 Nether brick blocks.
These are then derived from four Nether brick items in a 2×2 square  that's what's new for 1.5  and each Nether brick item is derived from smelting one block of netherrack. Multiply by four, we're going to need... are you ready for this? 11,336 blocks of netherrack! That's 177 stacks, plus eight more blocks. There's enough to fill three whole double chests, plus change!
To mine this, we're going to need a lot of pickaxes.
A wood pickaxe has 60 uses so 189 of them would be required. It mines netherrack in 0.3 seconds, and the mining would take 57 minutes (not counting pick changes, fetching more pickaxes from above ground, etc...). The required materials are 567 planks and 378 sticks (ultimately, 189 logs). This is obviously not practical.
A stone pickaxe has 132 uses so 86 of them would be required. It mines netherrack in 0.15 seconds, and the mining would take 29 minutes (not counting... you get the idea). The required materials are 258 cobblestone and 172 sticks (ultimately, 22 logs). That's more like it.
An iron pickaxe has 251 uses so 46 of them would be required. It mines netherrack in 0.1 seconds, and the mining would take 19 minutes. The required materials are 138 iron ingots and 92 sticks (ultimately, 12 logs). That's a lot of iron... more than two complete stacks. And there's already a lot of stone in the underground store...
A diamond pickaxe has 1562 uses so 8 of them would be required. It mines at the same rate as iron, and let's face it, 24 diamonds are worth a hell of a lot more than fourandabit stacks of cobblestone which is completely expendable.
A gold pickaxe has 33 uses (seriously!) so 344 of them (choke!) would be required. It mines at twice the rate of iron, but who cares? That's over a thousand gold ingots and only a complete idiot would consider this.
I think I'll stick with 86 stone pickaxes, and save my iron and diamonds, because this is a massive vanity project, after all...
Now, what about the smelting? We all know that coal and charcoal can smelt eight blocks each, hence 1,417 (22 stacks + 9) of each would be required. Lava buckets, then, would seem like the best way to go. These can smelt 100 blocks each (taking 16 minutes 40 seconds to do so, or 1000 seconds  convenient, eh?)  hence 114 lava buckets would account for all 11,336 of the netherrack blocks, and there'd still be change to smelt some (although not all) of the sand blocks. A 115th bucket and a single lump of coal would suffice, although the changeover between the lava and sand would most likely require a sapling or two in the interim.
I'm almost dribbling with the prospect of starting this (completely insane) project once 1.5 hits us. What's more, there's an extra incentive to mine netherrack, in that 1.5 brings Nether quartz that can be found amongst the netherrack in much the same way as coal can above ground. No idea how much use I'll have for it... maybe it'd be good for the windows instead of glass. We will see.
And finally, if you think this is a mad project...
