shaping foam rubber

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Forum topic by vicrider posted 12-12-2010 07:18 AM 9215 views 0 times favorited 45 replies Add to Favorites Watch
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179 posts in 2892 days

12-12-2010 07:18 AM

Topic tags/keywords: foam rubber shaping

Does anyone have any experience forming or shaping foam inserts to fit specific items? I would like to nest small tools in a shaped foam insert in a box. I have tried using poly foam seal, various sizes of weather strip adhesive backed foam, and a few other messy methods that were all abysmal failures. I haven’t been able to find any good google search results.

Any and all ideas will be gladly accepted.


-- vicrider

45 replies so far

View traupmann's profile


124 posts in 2780 days

#1 posted 12-12-2010 07:27 AM

I once used Saran Wrap around an item held it up with bamboo skewers from the kitchen put a heavy weight on it, and used spray foam that expands. then cut it with a hand saw. Worked OK, but I wasn’t expecting much perfection, just shipping it across country.

-- chas -- looking for Serta sponsorship to go Pro...

View Eric_S's profile


1565 posts in 3189 days

#2 posted 12-12-2010 07:36 AM

If I’m understanding, you could get various sized pieces of foam from a craft store in your area. They have egg crate style and flat foam shapes, hard and soft foam. It can be somewhat pricey though depending on the size and thickness.

-- - Eric Noblesville, IN

View crank49's profile


4030 posts in 2964 days

#3 posted 12-12-2010 08:46 AM

If you are talking about cutting foam rubber to fit a tool, I assume you don’t want to use the expanding type foam. The best tool for cutting foam, short of a CNC water jet of course, is a surgical scapel. If you can apply a slight pressure to the foam surface then slice with the scapel it’s too easy. Just please be very careful. Those blades are so sharp you can slice your hand wide open and never feel a thing. Been there, done that. Scapels are wonderful tools that can do amazing jobs, but they are very dangerous if you get careless.

View vicrider's profile


179 posts in 2892 days

#4 posted 12-12-2010 08:54 AM

Thanks, guys,

I have been attempting to make a form fitted indentation in the foam. Is there any way to pour a foam mixture over a mold?

I did try the same thing with plastic wrap and polyurethane foam (sealer), but the result was creased and looked terrible. I wonder how manufacturers do it?

I do have a set of scalpels, but my attempt to cut a recess with those looked worse than the poly expansion foam. very ragged.

-- vicrider

View Dennisgrosen's profile


10880 posts in 3108 days

#5 posted 12-12-2010 09:04 AM

I´m alittle curios about why and where you want to use foam becourse if its
to hold the tools in a drawer or stray then is the traditionel way makining a french insert
corvered with some feltclothe
and if you look over to the photho section they use a foam in the hardcases thats already
cut in 1inch sheets and every sheet is allso precut in small squares so its possiple to
make holes thats fit the single camera , objectiv ,blitz and this technic is used in many
different trades

just my 3cent


View crank49's profile


4030 posts in 2964 days

#6 posted 12-12-2010 07:44 PM

I obviously can’t see what your scapels look like and therefore can’t say they are, or are not, the type I am speaking of, but there is no way a true scapel with a new blade will make a ragged cut. These blades come wrapped in a little strip of cardboard, sealed in a sterile foil pack. Mine were made in Sheffield England. The blade style I use is called a #11. These things make a “scary sharpe chisel” feel like a putty knife. I’m talking beyond sharp. You can’t touch the edge of the blade without producing blood. I cut rubber molds for jewelry patterns all the time with these little buggers; and have the scars to prove it.

View vicrider's profile


179 posts in 2892 days

#7 posted 12-12-2010 09:33 PM

Hi Crank49,

as an ex-medical tech, I have real scalpels. the ragged edge comes from being unable to carve a molded shape in the bottom of the foam under the item I am capturing.

It appears that I may be trying too hard to get that custom recess look. Perhaps making a wood pattern of the object, then compressing the 1/2” foam under the pattern and cutting the foam in a compressed state may give a more professional look.

I make lots of small boxes for gifts and occasionally like to add unique items specially selected for that person. Rather than have the item rattling around in the box, my thought was to use some sort of foam to make a custom recess within the box. I also have a few long-time friends that have requested custom fitted boxes for larger items, really not suited for hand carved foam.

Thanks for all the thoughts, LJ’s, and I will keep this thread going for more ideas.

-- vicrider

View j_olsen's profile


155 posts in 3165 days

#8 posted 12-12-2010 10:02 PM


When I was in the Navy (aviation eletronics tech) we used a closed cell foam and made cutouts for our tool drawers so we could quickly invetory tools before buttoning up the repaired equipment—as you can imagine a tool being loose in a a radar conrtol box wouldn’t be a good thing

the material is similar to the pads that they use when gardening to kneel on—cuts easy and holds it’s shape
even the material they use for a sleep pad when camping

just a thought


-- Jeff - Bell Buckle, TN

View TopamaxSurvivor's profile


18265 posts in 3669 days

#9 posted 12-12-2010 11:00 PM

vicrider, I have tried to cut the foam before with the same results. I think you will have to compress it flat on both sides of the cut for best results.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View poopiekat's profile


4354 posts in 3728 days

#10 posted 12-13-2010 12:11 AM

I remember watching an episode of “Overhaulin” where they would rebuild custom cars. They’s send their interiors out to a custom upholstery shop where a very talented guy would ‘shave’ the contours into the foam before reupholstering. The bolsters on the bucket seats, custom sculpted dashes and contours on the arm rests were perfectly shaped before the vinyl went on. I just can’t seem to remember what tool he used, but I believe it was similar to an electric knife like for carving a turkey.

-- Einstein: "The intuitive mind is a sacred gift, and the rational mind is a faithful servant. We have created a society that honors the servant and has forgotten the gift." I'm Poopiekat!!

View FredG's profile


139 posts in 3690 days

#11 posted 12-13-2010 12:26 AM

Wet the foam, put it in the freezer and when frozen use a router to cut the contour.

-- Fred

View vicrider's profile


179 posts in 2892 days

#12 posted 12-13-2010 12:37 AM

Hmmmm, Fred,

I think I’m gonna try that next! have you actually done this?

-- vicrider

View FredG's profile


139 posts in 3690 days

#13 posted 12-13-2010 12:44 AM

Yes, I have Vic. Not too wet of course, just moist. And a cheap bit.
A Dremel works also.

-- Fred

View vicrider's profile


179 posts in 2892 days

#14 posted 12-13-2010 12:46 AM

Thanks for all the ideas, LJ’s

awesome responses.

-- vicrider

View Lee Barker's profile

Lee Barker

2170 posts in 2844 days

#15 posted 12-13-2010 12:54 AM

On some foams I have successfully used an electric knife. Usually two bucks at a thrift store, and easy to sharpen. Not good for the inside cuts you’re talking about, but I’ll go with the freezing idea and a grapefruit knife, also available, for less that two bucks, at a you-know-what store…

-- " his brain, which is as dry as the remainder biscuit after a voyage, he hath strange places cramm'd with observation, the which he vents in mangled forms." --Shakespeare, "As You Like It"

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