So, I'm brainstorming on my NoJoe '08 Lair project and I've got some questions about foamboard I see others using here and there.

How strong is it?
Can it be glued in layers to increase the strength, say to hold up a TerrorDrome?
How strong is it edge-wise? If I make walls, how thick would they need to be to load-bear?
What glue doesn one use to layer sheets together?
What to use to cut it with? X-Acto?
How well does it take paint, both with a brush and spraycan?
What about on the cut edges, does that exposed foam paint well?
How much per square yard?
What else do I need to know?

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Jimbo,
I just picked up two pieces. one 1/4" and the other 1/2" thick (each about $4.00 for a 20"X30" section). They're basically a foam center flanked by two pieces of thick paper. The boards seem strong enough to use as a base. So they would do the job for you. I plan of working with them today- hot gluing the sides, etc.
Hope that helps a bit,
John

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Can it be glued in layers to increase the strength, say to hold up a TerrorDrome?
Maybe..the thy can be found in different thicknesses, but my Michaels only carries a school project size one, and that would take 4 or more boards (and be costly to support the TD) It can be done though
How strong is it edge-wise? If I make walls, how thick would they need to be to load-bear?
Guess it depends on what you want weight wise, but I used double sided velcro and mirrors and figures and stuff on a wall with no problems at all

What to use to cut it with? X-Acto?
I do and it works out very well (again depending on the thickness

How well does it take paint, both with a brush and spraycan?

Never tried brush, by spray works fine, it will be a pretty bland color outcome from the little I have done. I use patterns and glue so far.

I didn't answer the other because I have not had any experience there yet.

michaels carries a specific type of blade for cutting foam core. its made to cut the form and one side of the card.

i wouldnt trust it to hold up a terror drome. for gluing pieces together, id go with spray adhesive or basic elmers glue, since the sides that will be bonding are paper.

to make walls, use sewing pins as "nails", re=enforced with masking tape, which can be painted over to hide.

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Here's a vital tip on cutting the foam:

http://www.hgtv.com/hgtv/cr_paper_craft ... 31,00.html

I also have a special blade that can cut angles:

http://www.dickblick.com/zz574/33/

You can spray paint the foam board as long as you prime the exposed edges of foam. The foam part can melt from the spray from time to time.

This tutorial might help too:

http://users.stratuswave.net/~wd8jik/fmb/foamboard.htm

Wow. That's a great tip. Hadn't thought of that.

The rest of the questions I can help a little with, though I'm far from a foamcore expert...I leave that to Cap, who is a wizard with the stuff.

Glue: I use Hotglue, I think that works the best. Easy to apply and dries quickly. Pretty strong, too.

Cutting: Definitely use an X-acto, and a SHARP blade. If the blade is even a bit dull, it will start tearing the paper and foam instead of cutting clean, which can affect how well the seams glue together and how nice it looks.

That's about all the help I can offer.

Justin

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Yes it will hold up the Terrordrome. I use 1/4" thick. The picture below it's sitting flat on a sheet.

http://holesnipe.homestead.com/cobramou ... terior.jpg

Yes you can spray paint it.

You cut it with an X-acto knife. It dulls the blades quick.

I use elmers glue and / or hot glue. Hot glue works quicker but IMO elmers is stronger.

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Holey:

A) Nice looking T-Drome
B) I take it the foamboard is a one-layer projecting forward under the front half of the T-Drome?

Thanks all for the help. I don't think I'll be starting any time soon, just brainstorming as much as I can first.

As to the 'edge-on load bearing' question; I'm talking something like this structure, with columns formed from layers of it to support a platform holding something like the T-Drome on top. Would the columns hold or what?

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I use similar methods as Zombieguide. I use elmer's glue and stick pins. It works great. Holds a suprising amount of weight too. I think if you doubled up the load bearing walls, you'd be fine. The only major foamcore stuff I did was the backpack on my Flash costume though. Spray paints very well.

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Not only can you double up on foamcore, you can get it in various thicknesses, too. If you're interested in 3/4", it's sometimes called "gatorboard". We used to use it in the art studio for large photo mounting, standees, that sort of thing. It's pretty durable stuff, but you'll need a utility knife to cut it. There's also a special glue available for foamcore or any other styrofoam called Styroglue. It's alcohol based and dries pretty quickly. I'd recommend pinning the joints of any large pieces together, as the others suggested.

I made an architectural model of a house once out of 1/4". I printed out the elevation drawings to scale and mounted them to the foamcore. When it was time to join the walls I simply trimmed about 3/32" of the first layer of card and the foam off the back of one of the pieces and hot-glued it together. The joints are pretty well hidden.