Magik arm armor

[candorpants]

I'm cosplaying as Magik in her costume from Uncanny xmen. I'm currently making the spiked arm armor.
I already built the base out of carstock. Its been reinforced with masking tape and it feels pretty sturdy. I'm looking to put something over it to harden it but I'm having a hard time deciding what to use.
I don't want to use bondo because it's such a pain to sand and the spikes will be unbelievably annoying since I don't own a dremmel.
I've never used fiberglass resin and am hoping to not have to deal with that mess.
I bought Elmer's Wood Filler but im reading that it needs a lot of sanding as well.
That leaves me with some sort of clay and plastidip. I'm thinking clay is going to be very heavy but plastidip might be too thin.

Advice would be greatly appreciated, I'm really stuck on this!

 

[Bogleo]

I would just use fiberglass resin, and if you want less fumes, use epoxy resin.

 

[candorpants]

Wouldn't I still need to apply bondo after that?

 

[Bogleo]

If you want it smoother, yes.

 

[Hazmat]

It might be better if you showed a picture.

I'm not crazy about using wood filler, It's basically the same amount of sanding as bondo it's not as hard when it dries and it's difficult to keep any of the edges nice and crisp.

 

[candorpants]

http://postimg.org/image/ygrdmbpjj/
Would wood filler be lighter than bondo?
What about some sort of Spackle like dry dex?

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Oops and here's a picture of the character too http://img4.wikia.nocookie.net/__cb20130207171133/marveldatabase/images/8/81/Uncanny_X-Men_Vol_3_1_Dell'Otto_Variant.jpg

 

[Hazmat]

I don't think wood filler is that much lighter. It is however a lot more crumbly and crappy. I haven't used Dry Dex or any other kind of spackle but from what I've seen it works pretty much the same as wood filler. I think Bondo is still the best.

 

[candorpants]

I know bondo will be (by far) the best quality but sanding all those small spaces is going to be a nightmare
What about paper mache?

 

[Hazmat]

You can try paper mache pulp. I haven't tried it personally but it should work pretty well. I've heard that the only problem is that you can't put it on too thick or else it won't dry properly and can rot.

 

[candorpants]

Last question! Im thinking of going the paper mache route and I'll need to finish it with a very thin layer of clay on top. Somebody gave me a link to porcelain finish clay and I was wondering what the difference is between that and paper clay or modeling clay. Is one heavier than the other or more durable? I don't have a problem with making the clay but I don't want to make it wrong and have it be a disaster