A primer on working with Wonderflex thermoplastic, by Elemental (amended).

Step 1: What Is Wonderflex?

Wonderflex is a type of thermoplastic that is shaped with heat. Thermoplastic has been around for a long time, but unlike other forms of thermoplastic you don't need to put this in your oven, and it doesn't smell like burning DEATH when you work with it. (It's non-toxic too, which cosplayers tend to ignore for their hobby, but is a nice side bonus anyway). It is also unique because, on the bias (diagonal line) it will stretch when heated, allowing full, round shapes and bell curves.

It has a mesh grid inside the plastic which allows it to stretch on the bias unlike other plastics. One side of the plastic shows the grid (a texture similar to duct tape) while the other side is smooth plastic with an eggshell-like texture.

Step 2: What Do I Need?

The basics of Wonderflex working is a hard surface (I'm fond of cement floors, and you don't want to work on carpet), Wonderflex , a pencil, some craft scissors, a heat gun (also known as a paint stripper and available at almost any Walmart/Home Depot/hardware store you visit, usually under $30), some paper and/or fun foam for patterning, and tape to help you hold pieces together for mockups and testing. Also, any reference image you can get your grubby hands on.

Step 3: What Can I Make With Wonderflex?

If you can think of it, you can probably make it. I have successfully made armor, chest plates, kneepads, staff tops, swords, and automail. My next projects include a shield, more automail, persocom ears, a Boogiepop Phantom hat and floaty-ribbon-o-death, and a bunch of small daggers and knives. With practice and work you can make it take just about any form.

Wonderflex and insulation foam staffs by Lauren and Hannah of Idjit:

Step 4: Advantages of Wonderflex

Wonderflex does things craft foam can't -- like bell curves. This means you can make a close fitting chest plate, or do exaggerated shoulder armor (from Clamp's Rayearth, or Yu-Gi-Oh!'s Dark Magician, for example). Unlike other kinds of thermoplastic, Wonderflex does not develop stress marks or wrinkles, and does not weaken along curves.

In photo: Automail fingers that circle the finger and are rounded, not square, at the tip.

And because there's no drying time for Wonderflex itself, unlike paper mache, you can work on a project until it's done.

Wonderflex is not fragile like Sculpy or Paper Clay. A staff top made of Wonderflex can be dropped, banged, or used to discourage an over-enthusiastic fanboy/girls and not react in the slightest. Stepping on it will probably crack your paint job, and may pop a joint, but the plastic itself is near-indestructible.

It can, under areas of EXTREME stress, over a period of time and with two loose areas rubbing against each other, develop a rip at the bottom, exposed edge. However this is easy to repair, and has only occurred once of everything we've completed so far, on the bottom edge of Seshoumaru's chest armor where the sword had been rubbing for two days. (The tear was a centimeter deep and didn't spread at all, even though it was under constant pressure.)

Step 5: What Can't I Make With Wonderflex?

Very thin pieces less than half a centimeter wide can snap under pressure, and will not support themselves upright unless given a double thickness.
Pieces such as Queen Beryl's headdress shown here, or Zoicite's shoulder detailing, would not be advisable.

Step 6: Is It Easy to Use?

Yes! Wonderflex is really quite user friendly. I had never worked with any form of plastic before using Wonderflex , and it took very little time to grow accustomed to. Because it is activated by heat, you can play with it at different temperatures to achieve different results. If you make a mistake, you can reheat it to reform it. Joints are made by heating two pieces and pressing them FIRMLY together. If you make a mistake heating the joints again allows you to separate them, but once cooled fully bonded joints will not separate.

Remember, I am not an expert! One of the reasons I'm creating this FAQ is because I'm one of the most experienced people in the cosplay community using Wonderflex right now, but that in no means makes me the resident-know-it-all. If you find another way of doing something, please let us know so this FAQ can stay updated with the latest techniques.

Step 7: How Do I Shape It? Can I Use My Bare Hands?

Wonderflex is suggested to be shaped while wearing gloves, but I find as long as you allow it to cool slightly I can shape with my fingers without problem. There IS some discomfort, and it does require a high heat tolerance -- if you are very sensitive, or worried, a pair of tight fitting leather gloves may be advisable.

Wonderflex can be shaped in three ways.

The first method is free form. Take your Wonderflex , heat it, shape it, let it cool. If it needs further shaping, heat it again. Easy!

The second method is a positive mold or form. This is what I use to make chest plates and automail. Making a duct tape form I shape the Wonderfle x over the form. This is also the method I suggest for staff tops with dimensions and things like Ed's spear. Create a shape out of foam (upholstery foam, or pink insulation foam) and cover it in a layer or two of electrical tape. Then simply shape the Wonderflex over it. This allows for large shapes that look hollow and are lightweight, and is especially useful if you cannot do the third method. The Luna and Solaris staffs shown below are made of this method.

In photo: Insulation foam covered in duct tape, Wonderflex formed overtop.

The third method is a negative mould. This is a hollow shape you push the Wonderflex into to take a form, similar to vacuforming. I have yet to try making negative moulds, so I can't comment on the process. I do know this is how Disney makes their Wonderflex items, and this allows for hollow shapes in any size.

As for cutting? I use plain old scissors, and a utility knife for shaving down tricky, tight curves.

Step 8: How Do I Pattern It?

I create my pattern first by experimenting with shapes drawn onto newspaper, then cut out of fun foam when I think I have the right size/shape. When everything is cut out of fun foam and pieced together properly, I then transfer the fun foam pattern onto Wonderflex . See examples below.

If I am making something with curves, like a chest plate or bell-curved shoulders, I make fabric patterns out of broadcloth to give me a better idea of how the Wonderflex will actually sit, as paper and fun foam only curve one way.

I have also seen great results by layering Wonderflex over fun foam for super-smooth and dimensional armor pieces.

Step 9: How Much Will I Need?

It's very difficult to guesstimate the amount you'll need. Finish your pattern first. Then, on concrete or a rug you won't mind putting tape down on, Measure out a rectangle 39'' by 57''. Start laying out your pieces on it like a puzzle, trying to keep them as close together as possible without touching. When that square is full start another one, and another, until you are out of pieces. The amount of squares you have is how much Wonderflex you'll need. I'd then add half a sheet more to that for mistakes and second guessing.

Also, ALWAYS keep your scraps of Wonderflex - I never throw it out, as even small scraps can be used later for reinforcing joints or raised details.

Step 10: How Do I Join Wonderflex to Itself and Other Materials?

Joins in Wonderflex are made by heating two pieces and pressing them FIRMLY together. If you make a mistake heating the joins again allows you to separate them, but once cooled fully bonded joins will not separate.

I use snaps, hot glue, epoxy, 'Goop' glue, and double sided foam tape (the GOOD stuff) to join Wonderflex to foam, fabric, and anything else needed. I've also used nails and screws for the spear, but I would suggest utilizing screws for the most part, or nails with a large head.

Note: hot glue and spray paint do not mix well. I.e., the hot glue will peel off and you loose the join.

Step 11: How Do I Paint It?

Any paint that's made for plastic works. I use Tremclad Hammertone Rust paint for my Automail, for the 'hammered metal' look, and for a highly silver/gold look I use Krylon Short Cuts Craft Enamel. If the Wonderflex has been gessoed acrylic paint will apply with no issues, and I've used fabric paint for raised detailing. Be aware that with paint, especially spray paint, you will get what you pay for, and cheap paint likes to flake.

From Amethyst Angel's Website:
One caveat about using Testor's paint. It will react negatively to vinyl. (Specifically, it will rub off onto anything vinyl that comes into contact with it.) This is important to remember if any part of the costume you're wearing is made of vinyl fabric or if you're thinking of securing the armor to your body with vinyl straps. (You could try using acrylic paint to paint your armor instead of Testor's--acrylic paint will NOT react negatively to vinyl-- but be warned, it will not stick to the surface of the plastic sheeting as well. You should sand the plastic first and then coat the painted acrylic surface with an acrylic varnish.) If Testor's paint should come into contact with vinyl and stain it, it can be easily removed with paint thinner or brush cleaner, so don't worry if that happens. (For the record, leather and suede will NOT react negatively to testor's paint, so it should be safe to use for your costumes.)

Step 12: Will It Lose Its Shape During a Hot Day of Wear?

No. Wonderflex WILL soften if left in a car on a hot day (not a good idea) and if you have painted your prop black (like Seshoumaru's armor) and leave it out under direct summer sunlight, again it may soften, but simply moving it back inside the house, or even under shade, will set it again.

If you are traveling long distances in a car that is not air conditioned, it is a good idea to ensure your prop is well supported and does not have any pressure on top of it. If it is small, pack it in the cooler with your food.

Step 13: Is It Flexible When Cool? Will It Break Under Stress?

As standard plastic, yes, it bends, but it will not bend out of shape. In other words, a sheet can be rolled for transport, but will unroll flat if untied.

It won't break under normal stress - don't build a ladder of the stuff, but it's very resilient; it will bend rather than break.

Step 14: Can I Make It Stronger?

Yes. Two layers of Wonderflex will bend much less, three layers won't want to bend at ALL. To create the immobile floating silver arch of Seshoumaru's armor, we used a piece of aquarium tubing for support. For swords I use wooden doweling to base the handle on and line the middle of the blade, to ensure it won't bend while being used. It also insures I won't have any weakness between the hilt and sword, as they're essentially one piece.

Seshoumaru's Spikes do not move in this costume at ALL, and are never lying against Jen's arm.

Step 15: Can I Use It to Build Large Props?

Yes. Something like Vash's arm would be very difficult without building some sort of support frame within it, and Wolfwood's cross would likely need dowel support along half the edges to ensure that the prop didn't bend along the joint 'weak' points while being used. But with the proper framework Wonderflex would work wonderfully, be very sturdy, and very lightweight.

I would
A) Decide that I would be holding it a bit higher, and therefore be supporting it on my SHOULDER, as opposed to just below the shoulder blade.

B) Decide where (and how) the arm would come apart for travel and storage.

C) Build a base form for what the interior would look like out of balls of newspaper and duct tape so that I could form over it. I'd make the main tube by wrapping that form with my sections of Wonderflex , and then building on top of that. It allows me to heat and modify pieces directly on top of my base without running the risk of the base falling in on itself while heated.

d) Build into the shape long wooden dowels, probably two running the whole length, possibly three for additional strength. While Wonderflex is strong, the arm is VERY large- and the sheer weight of itself could cause it to bend from stress. I may build each end's form out of foam for added stability.

e) Go absolutely batty gessoing to smooth it, and looking for the right feathers. Eventually give up and decide to make my own from organza and Wonderflex . XD

Photo: Here's a basic design for both the cross and arm.

As you can see, Wolfwood is easy- using the doweling keeps things in line while building and shores up joint support.

For Vash, red is doweling- I'd build a frame like that to support the weight of the arm (which really wouldn't be that much, all told, but would still need support) the purple is a COUNTERWEIGHT- something you are GOING to need for a prop that big that's intended to balance on your shoulder. The orange is Vash's 'arm', and the blue is just an idea of lining the 'feather; with a few strips of bonded Wonderflex to actually make it hold that shape.

The top right image is the silhouette of the arm- I'd make that, a touch thinner than what I want my final project, from duct tape and newspaper, and build my base overtop. Removing the newspaper ducttape form, I'd then make sure my dowel frame fit inside and would probably make STRAPS (green) to anchor it in several places in the arm (and since I always think of travel, and a whole dowel framework is just as hard as the whole arm to transport) figure out how I was breaking apart the doweling so that I could break it down if necessary. I'd put the base back into my form, and build the arm up from there.

I'd be tempted to make each end with insulation foam and duct tape covered in Wonderflex for stability, but that might be more weight than I'm interested in. I'd definitely experiment before deciding on one plan.

Step 16: Tips and Tricks

- For flat seams, heat the Wonderflex to the barely-tolerable range your fingers have, and then mash the join together, if possible on a flat surface. Using something to help you press without your fingers directly on the Wonderflex is good too.

- Don't use the heat gun too close to the Wonderflex, it will melt and be too hot to work with for longer periods of time.

- Pay attention to he Wonderflex as you heat it: it will begin to show when it is softening, the texture changing slightly under the light and if it is flat on the ground, the sides will attempt to warp for a moment or two.

- For raised detailing, fabric paint can be drawn on and then painted over.

- Try to keep brush strokes to a minimum when applying Gesso, and sand them down between layers.

- Split pins, snaps, and nuts and bolts all help make joints.

- If you haven't made the item before, try making it out of fun foam to pattern it out first.

- Save every scrap you have left over, as they can be small details and help support seams.

- Practice. Experiment. If it goes wrong, heat it and tear it apart and try again.