how do I use expanding foam to make a custom box for a magic wand?

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Burf7 years ago

Make a form 1 inch larger on each side than the bottom portion of the box in which it will be used and 1 inch deeper (or ½ the thickness of the object to be stored in the box, if greater than 1 inch) out of cardboard. Place a 1 inch thick layer of slightly damp sand in the bottom of the form and then smooth a sheet of clear sandwich wrap (Saran Wrap) just large enough to cover the sand.

Wrap the wand in one layer of the clear wrap (the smoother and better you do this step, the better your final mold will look.)

Place the wand on the covered sand where you want it to be when the foam mold is finished. Push the wand straight down into the sand a little less than ½ its thickness. Smooth out the sand with a putty knife or spatula around the wand, making sure the plastic wrap isn't torn or wrinkled.

Spray urethane foam insulation covering the wand first and working you way in a circular fashion out to the edges of the form.

Once the foam has cured you can trim the foam with a serrated kitchen knife or even better, with an electric carving knife, using the sides of the form to guide the blade. Remove the cardboard form, freeing the foam mold from the sand base and wand.

Carefully peel the sandwich wrap from the foam and cut it to the size needed for the box.

Fill any small voids with Spackle or wood filler, sandpaper to smooth any rough areas as needed and then cover with felt or fabric or spray paint.

I've used this method to make storage boxes for my precision tools and it works well.

RBobbitt5 years ago
For large objects
1. Line bottom of case with upholstery foam
2. Double wrap object in plastic bags
3. Spray outer bag with silicon spray
4. Insert object into case
5. Spray expanding insulating foam around the object
6. After curing and removal of object: shape, sand, or cut to finish form
7. Line with nylon furniture batting
8. Cover with fabric of choice.

Option for smaller objects (in my case, an antique pistol):
4. Spray foam into case
5. Push object down into foam before it cures

Another lining option :
7. Paint or spray adhesive into cavity
8. Pour in flocking in color of choice

Practice with a cardboard case and water pistol first.
Doing the box in halves:
-Put a large plastic bag (preferably 1-2mm) in one half of the case.
-Put the wand (or something if the same shape) in a bag.
-Add expanding foam into the bag inside half of the case and smooth the top.
-"Float" the bagged wand on top and press down lightly.
-Allow foam to cure (not long).
-Remove the bagged wand and the foam inside the bag.
-Trim the foam where needed.
-Gently glue crushed velvet (or another flexible fabric) around the foam to make it pretty because expanding foam is pretty ugly.
-Repeat for the other half but using the opposite side of the wand.
Eep!  Just saw a problem in the method I wrote.

For the second half:
-Place the wand inside a bag and inside the finished half.
-Lay a layer of plastic (2-3mm) with a bit of overhang on top of the finished foam side and tape in place.
-Place a bag inside the unfinished half.

Acting quickly:
-Fill the bag in the unfinished half with foam and smooth the top.
-Close the box and quickly remove any foam that escapes.

Finishing (same as with first half):
-Remove the bagged wand and the foam inside the bag.
-Trim the foam where needed.
-Gently glue crushed velvet (or another flexible fabric) around the foam to make it pretty because expanding foam is pretty ugly.

Note:  You may have to glue (or tape) the finished foam halves (that have been properly covered in fabric) to the inside of the box.
chicolet (author)  AngryRedhead7 years ago
Thanks for your super fast input.  I will give this a shot.  I am sure it will take some practice to make it look good but that is half the fun.  Do you know of any instructables that already feature my question?
I'm not sure, but a lot of people will make these sorts of things for gun cases and unusual instruments.  You can try running a google search if you want photos.  Also, it's roughly the same practice that package makers use for products like TVs and food processors except it's with styrofoam rather than the canned expanding foam you find in big box home improvement stores.  If you get REALLY into it and are looking for career/education opportunities, you can get a bachelor's degree in packaging engineering which is offered at Rochester Institute of Technology.  Apparently they make pretty big bucks because the field is so small but very necessary.
Mist everything with water that you want the foam to set well in. Water helps the foam cure.
Good to know!  Is this for all expanding foams or just for the "Stuff-It" type foams?
Just the canned stuff. The two-pack isocyanates don't need any encouragement !