Custom Foam Inserts Explained: CNC-Cut vs Pre-Cut vs Reconfigurable

Below: how to choose between those four paths, the exact measurements and outlines a foam shop needs before it can cut anything, and the pocket tolerances that decide whether gear sits tight or rattles.

Which type of custom foam insert do you actually need?

Start with one question: how stable is your kit? If the contents will be identical in three years, a cut-once insert is fine. If you swap lenses, add tools or change optics, a layout you can change yourself is worth more than a perfect one-off.

Pick-and-pluck (pre-scored cube) foam sits between pre-cut and DIY: the cubes tear out by hand, so you get a fast custom pocket with no tools. The walls are stepped rather than smooth, and plucked cubes do not go back in. If you want to compare that feel against blocks that lift out and return, the breakdown of pick and pluck foam versus reconfigurable foam goes deeper on both.

How are custom foam inserts made?

Four cutting methods cover almost all production work, and the method sets both the edge quality and how much setup the job needs.

• CNC routing — a spinning bit cuts pockets from a digital file. Handles internal pockets, blind depths (a pocket that does not go all the way through) and fine detail. It is the usual method for case inserts.
• Die cutting — a steel rule die stamps the shape. Fast per piece, but the die has to be made first, so it suits volume runs of a shape that will not change.
• Waterjet — a high-pressure stream cuts through the full thickness. Very clean edges, but it cuts through, not to a depth.
• Hot wire and hot knife — heat melts a clean edge through closed-cell foam. Used for straight cuts, trimming to size and hand-built one-offs.

A CNC shop needs a flat outline and a depth for every pocket. If you send a drawing, send it to scale with at least one known dimension marked. If you would rather skip the drawing, you can lay out the pockets yourself in the RAGAR foam designer and see the layout before it is cut. RAGAR makes inserts sized for Eylar, Pelican, Apache, Plano and Milwaukee PACKOUT cases, and also does custom CNC foam cutting for other brands from your interior measurements. Custom inserts are cut and shipped from Pomona, California.

How tight should each pocket be?

Foam compresses, so a pocket cut to the exact outline of an item will be slightly tight — and that is usually what you want. A pocket roughly 1/16" to 1/8" smaller than the item on each side grips it without deforming it. Go bigger and the item moves; go much smaller and you fight it every time you pack.

The exception is anything with a lens, a screen or a painted finish. Give those a relaxed fit and let a soft top pad do the holding. And always add finger access: a half-moon notch or a 1" relief slot at one end of the pocket. Without it, a flush-fitting item becomes a suction cup you cannot remove with cold hands.

Closed-cell polyethylene or open-cell polyurethane?

Closed-cell polyethylene (PE, including cross-linked XLPE) is the default for case and drawer inserts. It does not absorb water, resists oils and solvents, and does not crumble into dust the way open-cell polyurethane does as it ages. It holds a clean cut edge and it holds its shape under the weight of tools.

Open-cell polyurethane is softer and easier to cut by hand. It cushions fragile optics well and is forgiving if your pocket dimensions are slightly off. It also soaks up water and oil, and it breaks down faster in a hot truck or a damp garage.

A practical split: firm closed-cell foam for the cut layer that carries and locates the gear, and a softer pad above it to take up slack and press items into their pockets. RAGAR's reconfigurable inserts use XP cross-linked closed-cell polyethylene foam, with blocks that lift out and go back in — the design is covered by U.S. Patent No. 12,358,707 — so one insert can be relaid for a new kit instead of replaced.

How do you make custom foam inserts yourself?

DIY is a real option when the case is an odd size or you only need one. The order of operations matters more than the tool.

1. Cut a base layer first. A 1" solid pad on the floor stops anything from bottoming out on the case shell and lets you set pocket depth from a flat reference.
2. Lay out on the surface, not in the case. Arrange the gear on the pad, heaviest and longest items first, centered over the case floor.
3. Trace, then shrink. Trace each outline with a silver pen, then redraw the line about 1/8" inside it.
4. Mark depth on the blade. Tape a depth stop so every pocket bottoms out at the same level.
5. Cut walls vertical. Angled walls make loose pockets. Keep the blade perpendicular and let the tool do the work.
6. Add a top pad. A thin solid layer under the lid presses everything down and stops rattle in transit.

Tool choice: a long, thin, very sharp blade works on both foam types; a hot knife melts a sealed edge through closed-cell PE and is far cleaner on curves. The comparison of hot knife, blade, hot wire and CNC cutting covers which one suits which foam. For blank stock, RAGAR's uncut XLPE pads come in 1" or 2" thickness at 2 lb density in case-matched footprints — for example, the 17.75" x 12.5" uncut XLPE foam pad sized for Eylar SA00002, Pelican 1520 and Apache 4800 cases. Larger footprints exist too, including a 46" x 13.5" pad for long cases.

How do you keep an insert useful when your kit changes?

The most common complaint about custom foam is not fit — it is that one new item makes a perfect insert obsolete. A few design decisions prevent that:

• Split the cut layer into two or three pieces rather than one slab. Then you only replace the section that changed.
• Leave a utility pocket. A single open bay, sized to the largest item you might add, costs you a little space and saves a reorder.
• Keep small accessories in one shared tray pocket instead of a pocket per cable and battery. Small individual pockets age worst.
• Standardize depths. Using two pocket depths instead of six makes a later recut much simpler.
• Save your file and your measurements. If a layout gets cut from a drawing, keep the drawing. Reordering an identical insert in two years should be a lookup, not a remeasure.
• If the kit is genuinely unsettled, go reconfigurable. Blocks that lift out and go back in absorb change without any cutting.

One more thing worth asking before you order: does the quote include the base pad and lid pad, or only the cut layer? Those two plain layers are what stop gear from bottoming out and rattling, and they are easy to leave out of a comparison by accident.

More RAGAR foam guides

• Shadow Foam for Tools and Tool Boxes
• How to Cut Foam for a Pelican Case
• Pick and Pluck Foam vs Reconfigurable Foam
• All foam guides

Brand names and model numbers are trademarks of their respective owners. RAGAR is not affiliated with or endorsed by these brands; names are used only to describe compatibility.