The spray low foaming insulation works well, Common practice is:
Have the drawer/box container clean and ready.
Make up an insert for the above.
Place the items tools etc. in a layout you like.
Cover with a poly sheet plastic type drop cloth, tape at the edges, smoothing out major wrinkles.
Then with a piece of fabric of your choice, from Tee shirt material to faux velvet or stain type. Biggest thing is it should be soft and easily formed around the tools and plastic sheet.
Have an edge made up that goes around the insert, the height or depth of the drawer,again covered with poly sheet. Have another flat sheet(poly plastic sheet covered) to place on the top of the foam. So you have a flat bottom, and the foam doesn't stick to it. Weight it down with bricks, rocks or milk jugs filled with water.( 8.3 pound/gal)
If you are concerned about the solvents in the foam staining the fabric place another layer of poly on the fabric before putting the foam on then covering with the flat piece and weights.
Use the low expansion type canned foam as it will work to hold and form around the items. But will not cause a lot of over expansion. it also is semi soft not rigid hard like some of the other insulation foams.
As MM/Curtis said you can check out Alumilte foam products, or smooth on latex type make up appliance foam material my be soft enough.
Smooth-On, Inc. - Mold Making & Casting Materials Rubber, Plastic, Lifecasting, and More
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