Foam is Your Friend
We left the katana project with the basic build finished on the blade but there is one major part of the sword left to finish: the hilt. The main challenge here is that the hilt and pommel of a sword is usually curved at the edges and while plasticard and doubled up dowel are strong they are not flexible. It is at this point we must call on another trusty friend of the prop maker: craft foam. Craft foam is a medium to high density flexible foam that comes in a variety of colours, usually as A4 sheets. You can find it at basically any arts and craft store, often brand named as funky foam or something similar. The main reasons I use craft foam are its flexibility, thickness and affordabilty. You can also cut it very easily with a stanley knife or scissors.
Craft foam works best when layered with plasticard (via the use of hot glue) as it forms a durable, solid multilayered compound which is strong and light:
Above we see this effect on the cross piece that connects the katana grip to the blade. All 7 layers have been cut from the same template and although there is some deviation this step is followed by hot gluing a strip of plasticard to each exposed side of the layers to hide the messiness.
Craft foam also helps plasticard bend. When dealing with a part of a prop where a curved edge is required it is best to use lower thickness plasticard; preferably 0.5mm or less as it is more flexible. As foam is much more flexible than styrene sheet and holds hot glue very well it forms the perfect basis for curved parts of a prop:
This picture shows what will become the pommel of the katana (notice the crosspiece out of focus in the background. The hilt itself is made from cut up sections of electrical trunking flanked by pieces of dowel and taped together at either end:
The foam has been stuck to this core piece via the gradual application of hot glue. It was stuck in place at the centre of the trunking then more drawn out lines of glue were added as the core was rolled along a flat surface, forcing each line of glue into a uniform layer. This curved layer of foam then formed the base to which 0.5 mm thick plasticard can be stuck. You are probably now asking "why not just leave the foam without going to all the trouble of adding the plasticard?" It's a valid question and it has a valid answer; foam does not hold paint well at all and it has very little structural strength. Never paint directly onto foam. It will just rub off, even if you prime it. If your foam is the right color to begin with however - as was the case with the grip of the katana - there is no need for the addition of a layer plasticard. It was however added to the bottom of the grip to seal and hide the messy end shown above.
Mind the Gap
Once all of the structural parts of your prop are done all thats left to do before painting is filling in any gaps that may have opened during construction as parts of it flexed or pulled apart in odd ways. Usually these are small and won't threaten the structural integrity of the piece but they do look a bit rubbish if left unfilled. To deal with these we use modelling putty. It goes by many names; kneadite, green stuff, white stuff, grey stuff etc. It's essentially a form of epoxy putty that comes in two different coloured components (often blue and yellow) that when mixed form a shapeable putty that sticks to anything dry and gradually solidifies over about 12 hours. You can buy it at basically any model store (games workshop included if you like paying stupid amounts of money for very little) and it's great for filling gaps. Just mix it up, spread it into any gap with a wetted finger or the edge of your hobby knife:
Then leave it over night and sand the area with fine or very fine grade sand paper:
At this point you're almost ready to paint the prop, just make sure there are no stringy bits of hot glue left on it that will ruin the finish; you may even want to give the whole thing a sand with fine grade sandpaper to remove debris and prepare the surface for paint.
Spray and Pray
Once all your gaps are filled it's time for spraying! Always remember to undercoat your prop with a black or grey primer before any other colours go on (I personally use Games Workshop chaos black spray but thats possibly because I used to work for the company and old habits die hard) then go nuts with whatever spray you want to use. Just remember that your not trying to paint the whole thing in one go, some spray paints (especially enamel metalics) work best if applied in thin layers with 30min to 1 hour of drying between coats. Also when using masking tape always cover whatever your protecting completely in masking. Spray paint gets everywhere.
If you need to stencil anything I reccomend using decal paper; essentially an entire sheet of sticky back plastic that you can draw on. Its easy to get hold of and is great because you can use your original templates to mark out an exact replica of the prop-face you are stencilling onto:
here we see the original templates of the katana, the sprayed blade and the decal paper that will be used to mask off the blade when the final light sliver spray layer is added. Here's the finished effect:
Phew! We're done! the prop is finished, sprayed and ready to take to a convention! Or is it. Remeber to make sure you can't actually hurt someone with your prop before you take it to a con or it's probably just going to get taken off you. Smooth off and blunt any sharp edges or points and make it as light weight as possible. We don't want anyone getting hurt especially yourself. Mixing alcohol and samurai swords may sound fun, but someones probably going to loose an arm.
Also one last tip. Remember that everyone will think your props look cooler than you think they are, while all you may see are the flaws and inaccuracies that occurred while you were rushing to finish things all everyone else will see is a bad ass costume. You've had to be in contact with the thing for hours of blood sweat and tears; everyone else will see it for 5 minutes tops. So don't worry about things not being good enough. Go out and make cool things!
Stay Crunchy Internet