Planning on building a hard case for my Railboard at some point, I did some research on the foam to use to line it. Then, I ended up purchasing a 10-string rosewood with one of the old plywood hard cases. As often happens the foam in the case had deteriorated and crumbled. The PO cut some foam rubber to cushion the instrument, but that stuff is really hard to cut properly without special tools. Also, this material is likely to eventually deteriorate and crumble at some future point, so I figured I'd see what I could do to replace it.

The first thing I figured out is that there are two kinds of foam used in carrying cases of one kind or another. One is polyurethane foam, which is what we usually think of as "foam rubber". It is fairly dense (small holes) and soft, has an open-cell structure (it will absorb or pass liquid). This is often used for furniture cushions (though the high-end stuff has a denser core). This material is not very durable in the long term, and as I mentioned above is very difficult to cut cleanly because it is so soft. There are kits of tools that include heated elements for cutting this kind of foam that can be had for $30, but you have to decide if you're going to use it often enough to make buying the tools worthwhile.

Many listings online for this product include a picture similar to this that illustrates the texture of the material.



The other kind of foam, polyethylene, is somewhat similar to styrofoam, more rigid but very tough and flexible. You often find blocks of this kind of foam (usually white colored) used to cushion fragile items (like guitar pedals or other electronics) for shipping. It has a much coarser texture than the polyurethane foam shown above, and is closed-cell (it won't absorb or pass liquid making it somewhat waterproof). Unlike styrofoam it doesn't crumble or break. It's extremely easy (almost too easy) to cut with a utility knife, so no special tools are needed. It has high abrasion resistance so if your strings are a little "wooly" at the headstock, you'll be less likely to tear this stuff up removing and replacing your stick into the case. This is how many sites illustrate that material:



(Continued)

To better relate my experience to yours, the case I'm working with has inside dimensions of 44 1/2" Long, 7" wide and 4 1/2" high.

The piece of foam I purchased measures 54" x 16" x 2", but because the thickness is actually 57mm the thickness is actually closer to 2 1/4", thus two layers fits almost perfectly within the depth of the case.

Here is a link to the foam I purchased. I originally started to purchase it from the vendor (Case Club) but they wanted $68 to ship a $55 sheet of foam, so I bought it from Amazon. It was a bit more expensive but shipped free, so that was a win.

That sheet, if you want to go the "Full Monty", with solid foam throughout the case, will do the job. Cut two 7" x 44 1/2" strips from the sheet, stack them inside the case, cut the outline for your Stick in the top layer, a hole for the belt hook in the bottom layer, and Bob's your uncle...

However, I went with the three-piece approach with one block at each end of the case, and a narrow block in the center to support the shaft of the Stick. For this, that sheet was WAY overkill. I made the two end blocks from 18" (9" for each one) cut from one end of the sheet, which gave me four pieces measuring 7" w x 9" long by 2 1/4" thick. I was able to use the cut-outs from the top pieces to construct the middle support.

Here was the result:



Here is what I have left over!



However, for me this is fine because I still have plans to make a case for the Railboard when it arrives, so much of this will get used.

(Continued)

Here are some process pics. Note that I used a small utility knife with a new blade, fully extended. This was long enough to cut completely through the 2 1/4" sheet of foam. However, don't try to do it in one stroke. It's a challenge to keep the blade perpendicular to the face to create square-sided cuts. If you cut gently in multiple passes you run less chance of deflecting the blade off of vertical (the blade is very flexible). You can also cut most of the way through, poke all the way at one point and finish by "sawing" with the knife from the opposite side. Like I said, this stuff almost cuts too easily being very stiff, so you want to keep that blade firmly under control.

I placed the Stick on the top layer, careful to make sure that it was centered and parallel to the sides. I marked the foam with blue painter's tape, leaving a 1/8" gap, leaving plenty of "windage" around the instrument so it's easy to just drop in. I used a strip of scrap 1/8" hardboard against the sides to aid in positioning the painter's tape.

Once everything was cut to the right shape, I glued the top layer to the bottom layer with some clear silicone caulk/adhesive. I used tooth picks (which you can see in one picture) to keep the thin "wings" in the right position against the sides of the case while the glue set up.

I had to scoop out a bit of relief in the bottom layer on the bridge end to clear the mount for the belt hook. I also glued a 1/2" thick block into the center of the bridge end to bring the Stick up flush with the top layer and give the belt hook a little more clearance from the back of the case.

Hope this all makes sense, but let me know if anything needs clarification.

Very nice write up SteveS. All makes good sense to me. I really like that 3 section, head, tail & middle design. Minimum use of resources & lots of extra space for 'stuff' if required.

Was the 'convoluted' (polyurethane?) foam in the lid already there?

Yup. The PO put that in and TBH it's really the best thing for the top. It "squishes" nicely so it keeps the Stick secured. It's really easy to replace because a) it's so thin, you can cut the foam with scissors and b) it's really easy to remove and replace if it starts to deteriorate.

And yes, that 3-piece support is the bees knees. If you have a hunk of foam 2 1/4" thick and at least 14" x 18" you have exactly enough to do the job.

That looks so much better than the hackjob I did with the other foam. Plus you have a lot more room for other stuff (cable, belt, or anything else). Nicely done!

Thanks. That polyurethane foam is very difficult to cut because it's so soft, so you actually did a pretty good job!!

And yeah, I was going to fill it all, but then realized that some empty space would come in handy - and leave some extra foam for the next project.

Does the middle section actually support (i.e. touch) the back of the beam?

I should have posted sooner, but for your next job, a "electric knife" (the turkey carver) is supposed to work well. If you (or your mother, or your aunt, or your grandmother) has one stashed away above the refridgerator (because they were pretty bogus for turkeys). But it looks real nice good job.

It did, then I put that small block under the bridge-end, so it's probably about 1/8"/3mm above the support now. I'm not concerned about it, but I could slice off a bit of scrap and slip it under there. If I was putting it away for storage for a long time I might do that, but for day-to-day use, I'm not concerned about it being supported only on the ends.