A rookie mistake with hollow armour pieces. How to fortify/strengthen it?

[ZiggyGrimm]

Would you use fibreglass on eva foam?
I've not seen anyone do that, what are the results like?

You betcha! I do it with both fiberglass and carbon fiber. Here are some examples in various stages of build. The key is using proper adhesives to make them stick then using resin over top.

 

[he4thbar]

Dang, I need to make that shoe goo video.

Basically, it's a super strong shoe repair adhesive. Cobbler craft tools are surprisingly relevant if foam smithing, even barge was originally for shoes.
Basically you cover the back of your seams in shoe goo on the inside of the armor and it becomes nearly indestructible. The downside is coating the inside of a full suit of mjolnir can start getting expensive.

I did that with my Spartan and I've never had to repair it.

Agreed, I shoegooed all my interior seams on my ODST. that thing has been thrashed around and only repair i've had to make was on the boot covers because I bent way past the angle any foam could handle and went light on the shoegoe interior.

 

[Jeffw773]

I can't imagine the frustration of finally having something made and then watching it collapse

 

[VoidRunner]

Well I think this brings this post to a close. I ended up biting the bullet and investing in some 10mm foam which made the shoulder pad, strap, box thing much stronger and more solid. Definitely something I should have done from the start but it was a learning experience and I hope others can read over this and find useful information.

I'd like to summarise the post, adding my own input, focusing on constructing sealed foam pieces for armour, and probably props.

• Use 10mm foam as the bare minimum. Anything thinner than 10mm will have far too much flex and will barely support any pressure or weight.
• Identify the best flap/edge/face of the box to close last, as anything to do to strengthen the box won't be possible inside once the final piece is closed, so do everything through that opening before finishing.

• Expanding foam: Use 2 part liquid expanding foam, it's easier to work with and can be stored much longer than the pressurised cans. Also coat the inside with plastic wrap to stop the foam contracting and pulling the exterior inwards, it is sticky.
• Internal supports: Probably the fastest and cheapest way to strengthen a build, just layer foam into thick supports, or add popsicle/ice lolly sticks inside with hot glue.
• Shoe Goo: I have not used it but there is lots of support for it to make the seams extremely strong if you're worried about those parts. If anyone knows a UK variant please let me know.
• Hot glue: Good for fortifying seams too but be careful working in tight spaces as you close up your box.
• Fibreglass & Resin: I've used this on another project and can say it is great to make whatever is coated extremely strong. For a sealed box it could be coated on the inside and details added to the exposed foam on the outside, or the outside could be coated in resin/fibreglass with a filler (bondo) for details. My only warnings would be that some resins can get very hot when curing so watch out incase it starts warping the build, and if the build is flimsy at the beginning take care coating only the outside so it isn't a brittle shell.

Whatever method is chosen to strengthen your build, plan ahead first, you don't want to close the last part on the box only to find you've missed something... yes I've done that.

 

[he4thbar]

huh, fiberglass resin on seams, thats actually pretty smart, and probably cheaper then what I just did which was buying 7 tubes of shoe goo at the store. idk how flexible it is compared to shoe goo though.

 

[VoidRunner]

huh, fiberglass resin on seams, thats actually pretty smart, and probably cheaper then what I just did which was buying 7 tubes of shoe goo at the store. idk how flexible it is compared to shoe goo though.

Fibreglass + Resin has no flexibility, is extremely strong and durable, but if you try to bend the seam, it'll snap. From what people have said about Shoe Goo it's the better option if a seam is expected to have some movement/give.