WHAT YOU WILL NEED:
A picture of your fish
Maybe 10 sheets of 8 1/2X11 paper
Writing stuff (pencils, ball point pens)
Measuring stuff (ruler, tape measure, yardstick is helpful too)
Cutting stuff (box cutter/utility knife, scissors)
Taping stuff (2+ rolls of 1 1/2" masking tape, a roll of duct tape helpful)
Stapler (not a sissy one, you need a big silver Arrow construction one and a lot of staples)
Needle nose pliers
A LOT of cardboard and newspaper (I got all of mine from recycling dumpsters)
Paper mache (a package of flour, tap water, and a casserole dish will work)
Paint and brushes for finishing (latex house paint here)
PATIENCE (and a drop cloth is nice too)
Step 1: Getting Your Fish From Picture to Pattern
After you have your 'grid fish', find a center line down the length of the body. I chose a line that followed at about the center of the tail cuz that made sense for me.
Once your grid is drawn on, label your different vertical sections (in my picture I used alphabet letters, a through o). For simplicity, we will assume your grids will end up equaling 10" square, so the fish stretches slightly over a scaled 140" (in the photo you'll see the bill reaches over my last line a little bit.)
Get yourself a sheet of paper, and write down the section letters down the left side of the paper. For each section, you need to figure out how tall the fish (just the body not fins)) is at this point, and where the center line is. Keep in mind in the example, 1 square equals 10". Here is an example of two sections:
C section (front of tail) : Height 4", Center 2" from top 2" from bottom
G section (near center): Height 17", Center 6" from top 11" from bottom
Repeat this for all of your sections. Try to get close on your measurements, but fudging a little is OK. Remember that these dimensions are BODY ONLY, not the big top fin, lower fins, or even the tail. The exterior parts will be taken care of later; you are making essentially the fuselage of the fish, without anything else. For the mouth and bill section, you can estimate the dimensions with closed mouth if you want it closed. For an open mouth, I would read ahead and look at pictures before pattern making.
SO..... You have a sheet describing the dimensions of each body section now. How thick is your fish? I estimated width of the fish is about 2/3 of height through most of the fish. Around the head area it approaches 1 to 1 (just as wide as tall). I just guessed what would look good, and went with it. Take your section sheet and plug in the width #'s you want next to each one. Here are the two from above with what I picked:
C section (front of tail) : Height 4", Center 2" from top 2" from bottom Width 2.75"
G section (near center): Height 17", Center 6" from top 11" from bottom Width 11.5"
Time to transfer your dimensions to full-scale on paper, using the height, width and centerline measurements for all the sections. I taped pieces of computer paper together, and then using my measurements sketched out what I wanted each of the cross sections to look like. I only drew one HALF of each, so that when I transferred to cardboard I knew each half would be symmetrical (see photo). I then transfer from paper to cardboard, and then cut each section out. As you can see, some of my sections are not perfect ovals. The lumps on the top represent the body where it meets the dorsal fin; I wanted my body to follow closer to the shape of the actual fish, but feel free to just draw ovals. It would have DEFINITELY been easier for me that way.
As you make your sections, be sure to mark where the center is from your sheet above, and also divide the pieces from top to bottom. Do this on both sides of each piece; This helps a lot in the next step of ASSEMBLING THE SPINE.
Step 2: Making the Spine and Reinforcing Your Fish
The height of your spine pieces can vary but BE SURE THAT YOU FOLLOW YOUR CENTER LINE AS A GUIDE. Remember that center line you marked on your sections before? Use those as a guide as you move from section to section, so your body keeps its overall correct shape. You want your tail to taper nicely and the main body look consistent. In my pictures, you can see the body coming together. I did add a couple of extra sections for my own details between the 10" sections; Once again this is just for my own details.
Next you are going to add more cardboard between the sections to make the body more rigid. Before starting to cut and attach these via stapler, consider how you want your fish body to look when done. In picture two, you can see how the spine allows the fish body to flex left and right like a real fish. I wanted my fish tail to bend out a little to make it look less rigid, so I stapled in cardboard stringers between those sections (similar to how I installed the spine) in different lengths to make it curve out.
How many pieces of stringer cardboard you want to install is up to you; I ran them down both sides, and some on top. I also added some cross pieces on top of the spine to make the body more rigid. This ended up being plenty to keep the body stable for the next stes. You'll notice I have no sections where the head would have started; I added on my open mouth and bill section later (see coming steps) because I thought using this spine/section method for that would quite frankly look bad.
Step 3: Covering the Body in Cardboard and Getting a Head
Making the head... Well, I just kind of made this up. I made a copy in cardboard of the front of the body, and then just cut and bent and taped cardboard until it started to look good. In the picture you can see my upper-head/bill templates; I made the bill in a triangular shape (flat bottomed, angled sides) tapering to the end. You can use as much tape as you want because this will all be paper mache covered too.
As you work, hold your head up to the body to make sure it looks like it 'fits'. I reworked mine a couple times before I got it right. When you've got it looking good, just tape it right on with your masking tape. (see final picture)
Step 4: Paper Mache Is Your Friend
The size of your newspaper pieces doesn't matter, as long as they are FULLY SOAKED before you put them on. Lay each piece on and make sure it is as smooth as possible, overlapping edges as you go. I covered one side, let it dry, and then repeated on the other side. I only put two layers on in all; it is surprisingly resilient once it dries. The completed body once dry only weighs 5 pounds or so; it is hung on my living room wall with kite string around the center in the second picture.
As a side note, paper mache will not ruin clothes or stain, but it will make a mess. I used towels and an old comforter to keep my couch and floor clean(er).
Step 5: Adding Fins and a Tail
The Dorsal Fin (and rear fins): I cut straight down with my utility knife into the top of the fish, and made a channel down the center where I thought my dorsal fin should go. I then pushed a large cardboard blank into the channel, sketched out the fin, and cut to shape. I finished the fin with tape to hold it in place followed by paper mache over the whole piece. The two rear fins were finished the same way.
Side Fins: I did not want my side fins to look too flat, so after I mocked them on up on cardboard I added smaller pieces taped in for shape. (see photo) I added tabs to the fins that I could push into the slots I made in the body, and then paper mache'd them before I put them on. Once the side fins dried, I pushed them into the body in razor-cut slots, taped the tails close to the body, and then paper mache'd the bases of those fins to the body. Once this mache dries, the fins will stay close to the body rather than stick out too far.
The Tail: I made the tail just like the side fins, but with extra cardboard on both sides to make it symmetrical. After wrapping with tape and paper mache, i cut a verital slot into the tail end of the body and just pushed it on. Copious amounts of masking taper were then added to both shape it to the body and hold it in place, followed by paper mache over all of this.
For a convenience, using a swivel desk chair works well for holding the body while I added these parts. It is also easier rolling this twelve foot monster from room to room on a chair rather than carrying it and hitting the floor/ceiling/etc. The whole structure is fairly durable once dry, but it doesn't take a lot to bend a tail fin or kink the bill.
Step 6: Gills, the Front Pectoral Fins, Eyes and Primer
Gills: I added these as an afterthought, because it just really added to the look. I first made a gill pattern on paper, then transferred to cardboard that i rolled a little so it followed the body. Next I stapled the gills straight into the body, followed by tape and paper mache to finish.
Front Pectoral Fins: I waited on putting these in earlier because I could not set the body on a chair without damaging them. These are made from cardboard and tape covered in paper mache as well. To make these removable, I first put a temporary piece of cellophane over the body where it gets mounted. I then screwed the piece in with two wood screws; the cardboard will hold the screws quite well. Once in place, I paper mache'd the base of the fins smooth to the body and let it dry. (see photo) Once dried, I removed, trimmed and primed it. With these removed I can still set the fish down on my chair with no damage.
The Eyes: After marking the location for the eyes, I notched a star in the body and pushed in a cardboard blank to give the eye a sunken look. After unsuccessfully attempting an eyebrow look (shown in tape and mache) I tore it out and just mache'd the sunken eye. Primer filled it out nicely.
Step 7: Paint and Finishing
To hang the fish, I poked two holes in the back side and installed two expanding-head eye bolts. The cardboard and mache combined are quite strong, and the fish hangs now from picture wire strung between those two eyelets. Its entire weight is supported by one drywall screw right now, and I'd guess the entire weight is a around 12 pounds.
Overall, a fun project although it is very time consuming.