Like most projects it's best to start with an image of what you're trying to acheive. A quick scan of the web found the two images included below, the first is from Weta directly and is in higher res and therefore shows more details. The second is clip from the film which has the gun in a colour I prefer and shows it in a slightly different angle, both will be useful.
I now have a growing collection of costumes and props from the numerous fancy dress parties I've been to. This gun is rather large and I don't like the idea of moving it from house to house as we bounce around so I have decided to ebay it. If you read these instructions and decide that you would like to own this gun now is your opportunity....
This and all my other projects can now also be found on my own website at http://msraynsford.googlepages.com
Step 1: The materials
XPS foam, this is the pink loft insulation foam and is used to form the base of the gun.
Isopon P38 (The easy sand stuff), used to give a solid plastic coat to the weapon.
40mm plastic pipe, used as the core to the nobbly bits
8mm threaded rod (or similar solid bar) to connect the nobbles to the rest of the gun
Bottle caps, used to plug the pastic pipe
5mm dowel, details on the nobbles
Cardboard, used for details and tubes
Brown paper (any paper will do) used for the paper mache parts
PVA Glue, used as a protective cover to stop the solvents eating the foam
Hot glue, used to stick the foam parts together
Black and White acrylic paint. Many shades of grey to be made here, one of the joys of black and white weapons. Gun Metal coloured acrylic for highlights and weathering
Step 2: Naming conventions
The barrel, Stock and Handle are fairly standard gun parts so I'm on safe ground there.
The front of the gun has a stuck out bit which looks like the pilot flame for a flamethrower. I call this the spark generator (not to be confused with Sparc International mind you!)
The nobbly bit reminds me of the high voltage electricity stuff, so I call this the cascade tower.
The bottle on top of that I call a reservoir, conveniently placed to slowly drip stuff into the tower.
The bottom cylinder is below the gun so presumable injects stuff upwards, hence becomes the injector.
Finally the large cylinder on the back of the weapon reminds me of a power cell.
Step 3: Measuring up
To take this further you need to resort to some other method. I loaded the image into paint.net and drew a selection box around barrel of the gun. This told me it was 416 pixels long, the length of my forearm is 350mm long so therefore the image has a scale of 1 pixel to 0.8mm. By moving the selection box around the image I was able to measure virtually all the parts of the gun separately. I have included a quick doodle of my results and also a snapshot of my logbook containing more of my measurement details
Step 4: The main gun form
The barrel is 90mm high and 400mm long. One end of the barrel is cut with a notch to make room for the injector. The main diagonal is 90mm high by 280mm long, cut both ends at a 45 degree angle. The main part of the stock is 52mm high (to make it a square section) and 400mm long, cut the front of the stock at a 45 degree angle. Finally cut a piece of foam 40mm wide by 100mm long. This will form the L shaped part of the stock (different to photos). Use Hot glue to stick the pieces together, make sure each join has a good covering of glue and is pressed well together. Run the hot glue around the edge of the join to fill any gaps and to make the seam stronger. (You don't want the gun to break along these joins)
Cut a small 30mm long section of 32mm wide plastic pipe is inserted into the front of the barrel. Press the pipe into the foam on the font of the barrel, then use a scalpel to cut a circle where the pipe will site. Now when you come to glue the pipe in place it will slide into the foam and hold much better. Carve the foam around the piper to provide a rounded shape for the barrel.
Finally add a bracket to hold the cascade tower, this should be 100mm along the top, 90mm high and 40mm wide. Glue this in place with more hot glue, reinforcing the seams as you go.
As you can see from my images I did this stage slightly differently. I added some details into the stock as I was cutting it but if I were to do this again I would be do it this way and then slowly build up the stock with more pieces as described. I also added the injector bracket but again this is probably better done at a later stage so it becomes easier to work in that gap.
Step 5: The Handle
First thing was to create a pattern for my CNC to cut around. In my 3D modeling package I loaded the image as texture on a simple polygon. I scaled the polygon to the appropriate size and then started to use it to draw some splines. (Splines are special lines that my router will follow to cut out an object). The splines are converted to GCode through the program CamBam, and then run on my router with the program Mach 3. I'm sure if you have access to some kind of CAD machine this will already make sense to you, if you don't then you can come round and borrow mine (genuinely) or you're stuck doing it by hand.
Step 6: Adding shape to the barrel and stock
To keep the structure strong (it is the area you hold the weapon after all) it is made up from several triangular prisms, these shapes are strong in all direction and easy to construct.
Cut a piece of card 64.5mm wide wide 400mm long (this dimension can be made up with several shorter pieces). Score the card along the width to create the sides of the prism, these should be 5mm, 25mm, 24.5mm and 5mm wide. Fold the card and glue along the first 5mm length. Fold the card into a prism shape and glue this edge to the other 5mm wide edge. This should form a triangular prism with a right angle.
Repeat this process to create a second prism for the other side of the barrel and for 2 more prisms with sides of 5mm, 15mm and 14mm. Next cut a larger piece of card, 400mm long and 154mm wide. Score this piece into widths of 15mm, 10mm, 25mm, 54 mm, 25mm, 10mm and 15mm. This will wrap around the prisms and the barrel to form the desired shape. Glue the prisms to the larger sheet. A picture speaks a thousand words so I've included a doodle of this all.
Finally cut a notch out of the card in the same shape as the injector notch, then glue the whole shape to the barrel. This provides the added bulk to the barrel.
With that done it's time to add some shape to the stock. This I have less photos of but it is fairly straight forward. Cut some 5mm thick stips of foam from the block, this thin sheet of foam will be flexible enough to provide a curve to the stock. The foam will be the same width as the stock so start by building up the edges of the stock. Then create 2 'sheets' of foam by glueing 2 pieces of foam, 160mm long along the long edge. Carve the circular detail into this sheet and then glue it to the side of the weapon. Cut around the stock to make the sheet exactly the right size.
Step 7: Isopon for strength
Perform this stage in a well ventilated area, make sure you have all of your materials to hand. Once you mix this stuff together you want to get it onto the gun asap without having to find things.
Mix up a small amount of isopon based on the instructions provided with the tin. Smear it all over the weapon, I applied it to one straight section at a time, this way there should be no visible seems along the same face and any visible joins would be on the edges.
Once the Isopon has hardened you can begin sanding, use a fine sand paper and a sanding block to go over each of the surfaces. Once completed you will have a nice and smooth cover to the weapon which should be water proof and provides a great surface to paint on.
Step 8: The cascade tower
This was largely acheived through my well experienced use of paper mache. I honestly wanted to try something a little more complicated like casting the part and then making 6 replicas of the piece so they would all look the same. In the end I decided that I already have lots of glue and lots of paper so making the same part 6 times would cost me nothing but time, where as my efforts at casting would cost me money and may not work out. The end result is that not all the nobbles are identical but it's close enough.
The end of the cascade tower is made from balsa wood and attached to another bottle cap with a single bolt through the centre, this is hot glued into position at the end of the tube.
Step 9: The power cell
To form the basic cardboard shape find another object with roughly the right diameter (80mm), I used a plastic drinks bottle. Wrap the first a sheet of cardboard (A4) around the bottle and use some masking tape to hold it in place. Don't worry that the card doesn't wrap all the way around the bottle, the gap will be placed against the stock so it won't be visible. Once the first piece of card is stuck down you have something to glue onto. Smear a second sheet of card with a good covering of the PVA and water mix and wrap it around the first. Repeat this until you have 4 layers of card on the bottle and the card starts to hold it's own shape.
At this stage you need to make a second cylinder a little larger than the first. Wrap the next layer of card around the previous cylinder but this time don't glue it, hold it in place with some more masking tape. Build up another 4 layers on top of this one and wait for it all to dry. Once dry you can take the tube off the bottle former and seperate the 2 layers. Cut the bottom layer to the desired length and the top layer 30mm shorter.
Once the layers are seperated you can begin to carve some detail into the top layer. Draw the desired shapes on a flat piece of paper and then cut them out. To make four arrow shapes of identical sizes, draw one shape and cut it out, trace round this shape for the next 3 shapes and then cut those out too. Wrap the paper around the cyclinder and trace through the holes onto the card. Using a scalpel, carefully cut the shapes out of the card, being careful not to slice through your fingers.
To make the power cell end caps, first draw some circles of the correct size into the foam using a compass. Roughly cut the foam out of the block as a square shape. Carefully cut down to the line using a stanley knife to make lots of straight cuts until you have an octogon with the circle inside it. The cut the corners of the octogon down to the line, repeating until you get a roughly round shape. Sand the foam into a smooth circle. At this stage, cut the flat spot on the caps so that it sits against the stock.
To taper the end caps draw a line around the caps, 10mm from the end for one and 30mm from the end for the other. Hold the stanley knife at the desired angle (roughly 45 degrees) and cut from the line down through the cap. Turn the cap around 90 degrees and cut again, repeat until 4 cuts have been made, then cut those corners off, repeat as before until the shape is roughly circular, then sand the suface smooth.
Step 10: The Reservoir
Make 4 card board sheets roughly 30mm wide and the same width as A4 is long. These will be used to wrap around the base former. My tube was constructed around a pot of curry spice found in the kitchen cupboard. Laminate these 4 layers of paper by gluing them all together. Then add another 2-3 layers over the top again. This time they should all form complete cylinders around the object. Once dry take the top cylinder off and carve the detail into it.
Make the end caps from pink foam in the same way as before but this time the bottom end cap should come to a point, this will give you something to secure it to the cascade tower with.
Take the extra noble you made for the cascade tower, you will use this to attach the reservoir to the cascade tower. Use hot glue to fix the reservior to the top noble, more paper mache is used to cover the join between the two. The extra detail is added using tobing held in with hot glue. Don't worry about being too neat with the hot glue, once dry you can paint this a silver colour to make it look like welding on the pipe.
Step 11: The injector
Take an offcut of pink foam slightly wider than the roll, press the roll into the foam until it leaves an indent. Cut a circle out of the foam roughly in the centre of the indent. This should be easily wedgeable into the cardboard tube. Wedge and glue the foam into the end of the tube and then carve it into a rounded shape, sand it smooth.
To make the rings to go around the injector cut a 5mm slither of foam from the block. Foam this thin is flexible and ideal for the job. (You could carve this the same as the other circles but cutting the inside hole for the tube to fit into is a little harder). Wrap this foam tightly around the tub and cut it marginally longer than it needs to be. Slice the foam on both ends at a steep angle (image 3), this makes the join in the ring less obvious. Glue one end of the foam and wrap it around the tube as tight as possible, use masking tape to hold it in place. Make a second ring and wrap it around the first, this ring can be glued along the length of the foam to secure it to the first ring. Once the glue has dried you should be able to slip the rings off of the tube, this is important because the top ring of the injector has to be fitted while it is in the gap of the gun.
Paint the parts of the injector with some silver acrylic and black details and this part in then ready for assembly into the rest of the weapon.
Step 12: The spark generator
Unscrew the pen and empty if of the contents. Springs and ink can be saved for future project. Using a hacksaw cut the end of the Biro off. In my box of spare parts I happened to have a rubber sleeve that was about the right size for this job. Cut a 200mm length of the 4mm silicon tube and attach these items together with a little bit of glue. If you don't have a tapered rubber sleeve like mine then you could use a length of heatshrink shrink it at one end only.
Cut a piece of card to hold the pen in place. The basic shape should be large enough to wrap around the pen and then hold the pen 100mm away from the gun. Cut several pieces of card in a similar shape. Hold the first piece into a rounded shape using masking tape and then glue the other pieces over this first one. Laminating the card like this allows the piece to hold it's rounded shape once it has dried.
The two sides of the card are held apart wth some basla wood cut to the right width. The second piece of balsa should extend beyond the curvature of the card to provide a flat base to glue the spark generator onto the body of the gun. To add extra strength to cardboard I fabricated an H shaped piece of card to sit between the two sides.
Paint the shape with some dark grey acrylic ready for assembly into the gun
Step 13: The details part1
The rectangles that run the length of the barrel are made from framing card. This thicker card material was cut into the appropraite shapes and then aligned to a base piece of card, when complete the whole row was glued to the side of the barrel.
The large grey panel on the side of the weapon was formed from a thin sheet of pink foam. Once cut to the right shape the corners were rounded with sanding paper, and then the edges were tapered to give it the right look. This is painted a grey colour and then stuck directly to the side of the weapon.
The cross was carved in an offcut of pink foam. The offcut was quite thick so this piece was cut in half and used on both sides of the gun. The bolts were made with smaller again with pink foam. The small circles were glued onto the square and then the end of a paintbrush used to put dimples in the top. Once painted they look like the heads of bolts. I would use this method to put bolts in all the other places of the weapon, if I were to do this again.
Step 14: The details part 2
The heatsink on the top of the weapon, near the power cell was another block of pink foam. The fins of the heatsink were made by folding a piece of card and gluing it along the edge of the block.
The heatsink for the side panel was made in a similar fashion, this time 5 of the fins were made longer than the others and angled to point in towards the centre of the circle. The semicircular heatsink was made from pink foam, the impressions were made with the edge of some pliers, edge ridge points towards the centre again. The box and the circle were made with funky foam, this allows an impression to be made in the foam which shows after painting. In hindsight the circle should also have an inner impression. The tubing detail was made by applying some hot glue direclty to the backing plate, this gives a solid half rounded look to the item. The whole plate was painted with a dark colour and the gun metal paint was used to dry brush over the top, giving it a metallic look.
The saw teeth on top of the barrel are made from balsa wood, (as the close up shows how rough they are it would perhaps be better to make them out of foam), the shape they sit on was made from cardboard with a foam center for solidity.
Step 15: Painting and Finishing
This is now ready to form part the centre piece of your Wickers costume.
I'm sure there are many details left out of this instructable, ask me and I'll add them in. I'm also in the process of improving all the steps but these things take time and I wanted to get the weapon and the instructable released before halloween.
Thanks for you patience.