Its been a while since the last post here, and this website just had its first birthday in this format. To celebrate, I thought I’d make a post about a prop build… namely this combat mask, from the Game Army of TWO.
This article is a living post – it will be updated weekly as the project progresses.
No doubt by now you have read my article on working with pepakura, and also on taking the next steps towards working with resin and fibreglass (and maybe even my previous article on the daft punk helmet I was working on). This time around, I will be writing up a much simpler build, but taking it all the way through from paper to product.
OK, so the paint job is bad-ass and in the game it is patterned as if made from carbon fibre. As it is going to be used as a general photo prop, I’m not sure I’ll put this kind of detail into the paint work over coating in a CF wrap, but I’m sure opinion will change as the build takes place.
The model looks like this:
…and can be found here
Step 1: Pepakura
If you are new to pepakura, read this article on the basics.
So, you know the drill: time to break out the card-stock and PVA and get scalpel happy. I won’t dwell on the details of this step as its a pretty simple build, but some notes on the build are below.
This time around I used 300 gsm cardstock (eBay, £9 for 100 sheets). It is a bit of a pain to print with though as it is thick, and my LASER printer bends paper through 180 degrees, so check with your printer to see if it can handle this thickness, if not stick with 240 gsm which is fine for most printers.
Note my new cutting board: this is the old-school type you had when you were doing Design Tech at highschool. Its self healing and has a little bit of give – this softer board works wonders over my previous kitchen cutting board – the fact that it has a little give noticeably reduces stress on the fingers pushing the scalpel down, and also it reduces the dulling of the blade compared with cutting on a glass, metal or ABS surface.
About 4-5 hours after you sit down with several cups of tea, and a couple of re-runs of House, you have this:
I made a couple of these, and chose the best one: it is easy to get a twist on the nose, and also end up with assymetric eyebrow ridges, so take care and check. The good news is that I used the lesser model as a former to sit the selected model on to keep its shape whilst it sets when resining.
Step 2: Resin
We will follow the same drill as I outline in this article for both resin and fibreglass stages.
I used my standard fast-curing epoxy resin (from easy composites), and made use of the failed models as a former. The weather here is about 15 Celsius at the moment, and so not quite warm enough to cure it, so I mixed a hot batch (used a small excess of the amine hardener), and let it cure inside a box (to keep off the dust and wind). To pop the temperature a touch higher, I made use of those heatpads you get to help with muscle aches (a Poundshop special!), and stuck a few inside the box. My thermometer read an internal temperature of 24 Celcius, and after 5 hours the model was solid but a touch tacky. The following morning it was tack-free and pretty rigid.
The resin permeates the cardstock pretty well, and it was rigid and ready to fibreglass.
Step 3: Fibreglassing
Moving on from the resined model, it was time to increase the build strength with fibreglass composite. For this task I used 160 gsm glass twill weave (from here). This was my first time using this particular type of weave, and I was surprised at how easy it was to work with.
Unlike fibre-mat this is neat and easier to work with – it is less bulky too. When working with woven fabric, get some sharp scissors (best have some solely for this task), and be sure to wear gloves and wear at the very least a dust mask when you cut it. I cut my sheet into squares before preparing the resin, as you dont want to mess around with this when the resin is live. A note on the woven fabric: the edges can still fray, so scissors need to be sharp and don’t drag the edges or it will un-weave a bit.
Get yourself a Tupperware pot (with lid) and keep your cut pieces in it. Keep it secure with your other fibreglass kit, and you will never waste any pieces as you can save them there for the next build.
The fibreglass work took about an hour to do properly, ensuring piece overlap and also reinforcing areas I know that are going to be under strain: the nose bridge, and the eyebrow ridges. For this model, do not fibreglass the eye pieces as we will be cutting them out. Be sure to reinforce the edges of the eye sockets as we will be doing extensive work here in the body building phase.
Back into the box to cure, and about 6-8 hours later it looked like this:
So now that the model is ready and set, its time to press on with the clean up and then the body work…
Step 4: Clean-up
So as you can see from the image above, the edges need cleaning and also the eyes need popping out and tidying ready for the body work…
OK first thing’s first: you’re going to want to wear some thick gloves, and also a dust mask, as we will get some glass fibre / dust kicking up. I have learnt through experience that manual toothed tools like saws tend to do better than automatic cutting disks for keeping the dust down.
Firstly, I went around and tidied the edges of the mask with some sharp scissors. When fibreglassing the model, I should have folded the fibre over the edge and back onto the outside, but hindsight is 20:20 – so my clean up was good, but I left a few strands of unsealed glass (which is a hazard still). I sorted this by running a bead of superglue along the edge of the mask, which sealed the glass.
After than was done, I went about cutting out the eye pieces. As aforementioned, I avoided fibreglassing the eyes and left the centre of each eye piece unresined, and so it was easy to pierce with scissors and drop a coping saw blade through and cut to the edges by hand. The eye pieces then snapped out, and left an OK edge. I then sealed any glass frays with superglue as before, to give the final superstructure:
Step 5: The first fill
SO before we dive into filling the outside of the mask, we need to key the surface thoroughly – some 160 grit will do it very well, and leave a nice grippy surface for your body filler of choice. In the US everyone tends to jump on a product called Bondo for this, its used for car body repair and is fast curing, strong and light weight. It is also very smelly, a bit hazardous and unobtainable in the UK. The UK alternative (equally smelly and toxic) is called “Isopon” which you can get from Halfords. However as on this build I am trying to avoid polyester resins, I have decided to body build with good old Polyfilla FINE filler – I learnt the hard way that you really NEED a fine filler if you are going to use a Polyfilla type. WILKO’s extra fine (about £3) is really great for this task, and it sticks to resin pretty well.
Remember the rule that less is more and try and not add too much new mass to your mask with unrequired mounds of filler. I made a skim layer over the entire mask, which was not very neat, but enabled me then to build onto it (filler sticks to filler better than filler sticks to resin).
31 Mar 2014: Filling, sanding, filling again …. (and sanding again).
Step 1: make sure you have good ventilation – this is gonna get dusty. I have a palm sander that connects to my Dyson, which helps a bit. Dusts masks at the ready…
OK, so I left this last time where I was applying the first fill… which looked like this:
A very rough fill, just to give some ideas as to the shaping that needs to be done from the mask. A quick sand (120 grit will do) to help shave the rough edges down, gives you a nice look as to where you need to build up the filler to get the desired shape.
No matter how good your model, there will be a little asymmetry that you will want to correct by building up and sanding back a few times to get it right – and so I did, little by little in areas that needed it. I also used filler to make the edges more safe by making a thin layer along the edge and also on the edges on the inside – This made it a lot easier to handle.
The model now was a lot smoother but there are still areas that need addressing before I got in there with detail work- one side is a bit more angular that the other on the forehead: out comes the fine filler again and some 400 grit sandpaper. I also neatened up the edges by leaning it on a flat surface, and then filling with a finger to the surface to make seal, and then lifting the model clear once it had set (see image below), and then sanded flat.
After a good sanding down with 400 grit, the defects are getting a little harder to see (little 0.5-1 mm pits and so on), and so I found a great way of seeing them better: I got a USB LED lamp (yet another PoundShop special), which enabled me to cast shadows where the pits were by putting the light side-on – this actually really helped.