We had heard about a certain contest, and decided to come up with an entry. After a couple failed ideas, I got the urge to play through Bioshock again. Then I suggested: Why not build a model of rapture in a fish tank? Thats pretty awesome. And so here this thing is.
The main theme of this project is "What Is Cheap Or Free Or We Have Lying Around". Most likely, its going to be tough to find some of the materials we used, but hey, necessity is the mother of invention, right? And every tank would be unique! Yay unique!

The format for this is how we did it. There may very well have been easier ways to do this (a 3D Printer would have made it WAY easier) but this is what we did to get the final product. Suggestions for improvements are welcome!

Step 1: Materials

What we used:
Broken Acrylic Fish tank (Missing lid and back panel)
Acrylic panel (Given to us)
White Sand (From Ace)
Wood (Maple Door Jam and Plywood, that we had laying around) for Buildings
Wood Glue (around the house) To make the buildings
Yellow Plastic Tape (Ace) for Windows
Hole Punch (From Walmart, trust me the pain of an old one isn't worth the pain) for making the Windows
Polyacrylic Sealing (From around the house) to seal the wood
Acrylic Caulk (Ace) so the water stays inside the tank, and buildings to the bottom
LEDs and Resistors (Radioshack) for lighting (2 green and a pack of 20 assorted)
11 AAs (Walmart) for the LEDs
12V AA Battery Holder (Ace)
Black and Bronze spray paint (Walmart) For a basecoat on the buildings and the statues
Cannula Tubing (Given to us) for the passageways between buildings
Bottle of Green Interior Paint Tester (Walmart) to drybrush onto the buildings and statues
Secret Ninja Force Wall Walkers (Dollar General, $1) for the statues
Plastic Christmas Wreath (from the garage) for the ocean floor ecology
Fish (Walmart) to make it a real fish tank
Air Pump (Walmart) to make bubbles
Imagination, to ignore all the mistakes

Other tools we found useful:
Table Saw
Chop Saw
Belt Sander
C Clamps
Super Glue
Windex
Paper towls
Paintbrushes (One to paint on the sealant, and another for the drybrushing)
Scissors
Wire Splitter

Step 2: Cutting and Glueing the Wood

After measuring the tank (16 high, 36 wide, 12 long) we figured out how many buildings we wanted, which involved more on the spot decisions than planning, much to the chagrin of those helping us. We tried to have a fairly wide variety of sizes and shapes. We used a double layer of wood for most of them, and 4 layers for 3 of the buildings. We ended up with a total of 15 buildings, and a number of smaller bits and pieces to add on.

Protip: We had several pieces of wood the same width, and after we decided that we were going to use 2 pieces per building, we cut both at the same time so they fit perfectly.

After cutting the buildings to size, we glued them together. Most were fine just sitting until the glue was set, but a few (Especially the 4 layer buildings) needed to be clamped to set correctly.
After leaving the buildings to set overnight, we sanded them down so the off angles and the flaws were fixed. Some of the bases were still off, so we squared them off with the table saw again.

Step 3: Paint the Buildings

We basecoated everything in black spray paint, and we ended up using about 2 1/2 bottles. We used satin so the buildings wouldn't shine more than the windows, but ran out after 2 cans. We went back, and they had run out of satin, so we finished off the buildings with gloss black.
Next, we drybrushed the green on. For those of you who don't know how to drybrush, prepare to be enlearded! I also encourage you to look for another source if you don't understand. The internet taught me!

The point of drybrushing is to highlight edges and any raised surfaces. First, you want a brush you don't mind being frayed, and a good amount of paint (this tends to waste a good amount, even after you get good at it). Get just a bit on the brush (enough to cover the tips of the bristles) and wipe the excess off: you should have just enough that a brushstroke only leaves a bit of paint (you can see how much I wiped off in the picture). Now you want to 'sweep' across the edges of the buildings. When you stop seeing paint, go back and add more and wipe the excess off again. This can take some patience, but the results were fairly good, in my opinion.

Step 4: Make Dudes!

If you examine the screenshots of the outside of Rapture, you might notice that there are large statues. We decided that we needed those too, so after failing to mold some we decided to buy some cheap ones and paint them.

It may be fairly difficult to find the same ones, so would encourage you to find your own. I sanded them so they would take the spray paint better. I then basecoated them with black, and then coated them with the bronze. I then used the same method of drybrushing I used in the previous step. We decided to wait until after we had sealed them to attach the guys to the wooded buildings, so we didn't accidentally miss anything.

Step 5: Windows and Sealing

For the windows we went with hole punching yellow scotch tape and aligning them along the indents of the buildings.

Next, we applied three coats of sealant. Make sure whatever you pick up won't etch the paint off in the process and you should be good.

Step 6: Attaching the Buildings, Adding the Sand and the Tubing

Caulk was our best friend in this project. Depending on your surface you'll want to get the right caulk. For us Acrylic was the easy choice.

Sandpaper can also help the adhesion. Just rough up the spot you plan to stick a building, apply the caulk to the building's base and slap it down.

Then sit back and admire your work, you have at minimum 24 hours before anything should be disturbed.

Depending on the caulk you can either humidify, fan, or heat it to speed the process. It should say on the container.

After the buildings dried we added tubing between the buildings then foliage and sand to the ocean floor.

The tubing was cut into segments (longer than we knew would work) and then shortened so it would attach between the buildings easily, then super glued down. I tried to use the tubing to bide some of the imperfections in the wood.

The foliage was cut bits from a plastic wreath, puttied and glued down to the base. Be careful to make sure that when you add sand, the foliage is tall enough to poke through!

We added the sand by cupping it out of the bag, and using a brush to disperse it a little more accurately.

Step 7: LEDs

The 20 pack assortment from RadioShack was hit or miss. You'll definatly want to grab some resisters and the battery packs make
life much simpler. We managed to take out around half the pack deciding how much power was the proper brightness for each LED.

To simplify this step I recommend splurging the extra couple cents and purchasing the LEDs with resistors. If not then the 500 pack of resisters should last for the foreseeable future of your DIYs.

Electrical tape was used in final attachment to the tank, two red LEDs next to Ryan Towers and 6 green around the sides.

Pictured is the 8 pack AA which comes out to a 12V series set and makes the green LEDs nearly yellow without a resistor. For wiring speaker wire is always my favorite for providing some shielding and being readily available from other projects (as a bonus its color coded for positive and negative).

Step 8: Just Add Water!

Then add water!

A lot of water.

Make sure it is proper temperature so your next step isn't a mass fish burial. Somewhere around 72F (22.22C) is what our little goldfish were good for.

Step 9: Fishies

We were told to put the bag of fish into the tank and let them reach the same temperature then release them all.

That sounded far too responsible and we immediately let them lose in their new home!
(Also the water was already the correct temperature.)

The water stirred up the sand pretty well in the process of adding 30 gallons of water but there are 25 fish and a handful of LEDs arranged.

To get the deep sea ocean look two drops of blue did the trick nicely. It also looks neat while it disperses.

Step 10: Profit!

Some of the things we tried and found out didn't work:

Neon Signs: We had made about 10 signs out of neon flag tape and some bits of ruler, but found out that the ink we had used to draw out the lettering ran terribly when we added the sealant. Maybe there would be an easier way, but we ran out of time to discover it, and ended up having to scrap it.

Water coloring: After seeing the water with food coloring in it, it had a cool look but blocked all the light from the LEDs. One or the other would work, but both together didn't.

Thanks, and have fun instructables...ing?

Video!