Foam Board for Carving?

So I’m looking for advice from anyone who has carved detailed surfaces out of foam.

I’m looking to cut a topographic map, but I think since it will be painted I don’t need it to be made of wood. Plus I will probably screw up alot learning CAM. I have autohoming, so I can do multiple days of carving on a single piece, hopefully.

Q: What is a good foam to use for 3/4" to 1" thick surface carvings?

I can get 3/4" maple veneer faced MDF from a local wood supplier for about $90 (4’x8’ sheet), but I am unsure if that will be as easy to carve as foam. certainly the carved surface will be dense, but I’m just looking for aesthetics in the end, as I will likely airbrush paint the surface so assuming foam would be good as well.

I will have it in an enclosure, with HEPA dust collection drawing air out of the enclosure.

BELOW you will find write-up of various types of foam, from a railroad modeler, which I found informative.


Here is a list of some of todays available foam materials: The average modeler is not familiar with some of these versions. For modeling, my favorite is Gatorfoam or gatorboard. (Same thing)

Polystyrene (in softer, 5psi pound versions) - “Styrofoam” Dow Chemical - is the soft disposable foam used in cups and packing material and is too soft for permanent use.

XPS - Rigid Foam Insulation - , Extruded polystyrene sheet - Dow Chemical is Blue, Owens Corning is pink and includes different densities Foamular 400, 600, and 1000 is Owens Corning’s 40, 60, and 100psi foam. It is the same —measurably identical— as Dow’s Highload 40, 60, and 100 There are also others Pactiv Greengard (light green) and RMax Thermalsheet in light gray.

Gatorboard - Laminated Polystyrene & Luxcell - Gatorfoam® foam board is an extruded polystyrene foam board bonded between two layers of Luxcell wood-fiber veneer. It is very stiff, rigid and heavy duty, yet a versatile foam board which is perfect for many model railroad structural uses. It comes in thicknesses from 3/16 to 2 inches thick! Most modelers have never seen Gatorfoam. It is used in sign shops, and is only sold retail at a few art suppliers.

Ultraboard - Laminated Polystyrene & Styrene Face - UltraBoard is a premium sign material which has styrene facing instead of Luxcell, however, due to the flexible nature of styrene, it is not as rigid as gatorboard.

Foamcore - the common “Paper-faced Foam Board” you see everywhere. It consists of three layers – an inner layer of polystyrene foam clad with front and back outer facing of either a white claycoated paper or brown kraft paper. It is Vulnerable to moisture - Warps and very substandard inexpensive foam board compared to other boards. Craft people find ways to use it and like it, but doesn’t have permanency of other products. Ideal uses - temporary structures, mockups, templates etc

Structural / Core Foam - all sorts of high end honeycomb, carbon fiber aerospace etc - the aerospace industry has a whole catalog of industrial grade, very expensive foam panels for a variety of applications for aircraft and spacecraft.

RF & Microwave Shielding Foams - black, coarse foam used for various rf shielding uses. Not generally suitable for modeling applications.

Falcon Board - 100% recycled printable paper product with a paper honeycomb core and smooth white exterior - rigid and cheap - good candidate for backdrop support 1/2" and 3/16" thicknesses.

Rigid Urethane Sign Foam - 3D signs graphics and displays - similar to below - designed for CNC machining - aka “High Density Urethane” - The tighter cell structure of the new Precision Board Plus High Density Urethane foam board has produced improved machining characteristics, Higher machine feed rates are easily achieved compared to wood, epoxy and alloy substrates.

Sintra - PVC faced, hard foam core - which is heatable and bendable Sintra is a lightweight rigid board of moderately expanded closed-cell PVC, manufactured by 3A Composites USA Inc. available up to 19mm (.750) Has some interesting applications in model building.

Phenolic foam is a lightweight, high performance, thermal insulating foam that possesses excellent mechanical strengths.

Polyethylene Foam (PE) is a strong resilient closed cell foam. Used for shock absorbing, vibration dampening, loose fill, and cushioning.

Reinforced Polyurethane Foam - 3M Reinforced Polyurethane Foam, a lightweight and rot-resistant alternative to plywood for use in structural and semi-structural applications. These polyurethane foam boards with fiberglass reinforcement provide high strength in applications including marine, transportation and general construction, with a weight savings ranging from 30 to 60 percent versus plywood. If you need something really tough, this is the way to go.

PolyISO FOAM CORE - Polyisocyanurate - Trymer® - Polyisocyanurate foam is a rigid foam that has the highest insulating values of any conventional foam insulation commercially available today and often has a glued surface facing for convenient application.

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At my last job the artists used Renshape. Not sure it is what you need but it is the only thing I am not seeing on your list. It carves well, and can be sanded. It does have a textured surface though.

There are more densities.


Thanks, I couldn’t remember where I read it a couple months back, or what material it was. HDPU I believe is the acronym now, same stuff you linked to.

The poster was saying that everything you see in Vegas that looks like carved wood is made from, I believe the term is HDPU; I will start looking at how to get a smooth surface without sanding. Would be impossible to sand 3D mountains.

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You could always thin epoxy resin with MEK, that turns it into more liquid, not too much just a little. The other way is to use Goop, marine version thinned with Toluene. This you can thin as much as you want. Toluene is the base of goop. The awesome thing about this combo is you can paint on the toluene and make the goop as thin as needed. I use this for coating over label maker labels on bottles, containers, and anything labels normally don’t stick to well. The other advantage is nothing (loosely interpreted to the usual suspects iso alcohol, acetone, etc) affects the final dried product.

Let me know if you have questions, science is fun.


Yeah so I’ve thought about a thin but quick setting epoxy resin.

I keep two gallons of table top resin around, but it’s still a slow cure. Doesn’t really get thick enough to not run vertically (by gravity) for id guess a good 3+ hours.

I’m going to try 3D printing UV resin… paint it on let it self smooth a bit, the zap it with UV light. Bam, smooth surface.

I’m also going to try and silver foil the landscapes then antique glaze them.

So question: what kind of epoxy and what volume ratio of MEK to mixed epoxy do you recommend ?


No more than 25-30% MEK added to the epoxy, but this is a kind of know it when it is too much things.

Renshape is $370 for a 4’x8’ board… wowsers that spendy for foam!