Pick-and-pluck foam is the most democratic thing about a hard case. A grid of pre-scored cubes, a lid layer, and a base layer, and anyone with ten minutes and a steady hand can build a custom interior. It is also the source of most of the sad photos we receive: a camera rattling in a cavity twice its size, a drone wedged at an angle, a foam block that came apart in one lump because someone pulled at the wrong corner. ✂️
The material is not the problem. The method is. Below are the ten mistakes people make when cutting pick-and-pluck foam, how to avoid each one, a section on the foam materials themselves, layouts by profession, and an honest section on when to stop cutting and order CNC-machined foam instead. We make both, so we have no reason to push you either way.
Part 1: What pick-and-pluck foam actually is
Most Peli Protector and Air cases ship with three foam layers: a thin convoluted (egg-crate) layer in the lid, a thick pre-scored block in the middle, and a solid base layer underneath. The middle block is the pick-and-pluck layer. It is polyurethane foam scored on a grid of roughly 12 to 15 mm cubes, cut almost but not quite all the way through. You pull cubes out to create cavities; the base layer stays under the equipment; the lid foam presses down on top.
It is a clever system. It is also soft, it tears if you rush it, and it cannot be put back once removed. Everything below follows from those three facts.
Part 2: The ten mistakes
1. Starting to pull before laying the equipment out 📏
The classic. Enthusiasm meets a fresh foam block, and the first cavity is dug before anyone has decided where the second one goes. Lay every item on the foam first, in the arrangement you want, with a finger's width between items and two fingers from the walls. Photograph it. Only then trace and pull.
2. Cutting to the exact size of the object
Foam is meant to grip. A cavity cut to the object's exact dimensions will fit loosely after the first few openings, because polyurethane compresses and the cubes around the cavity relax. Cut the cavity one cube smaller than the object on each side, so the equipment presses gently into the foam walls. It should take a little effort to lift the item out.
3. Cavities too close together
A single row of cubes between two heavy objects is a wall that will tear the first time the case is dropped. Leave at least two cubes between cavities, three between heavy items like lenses, batteries or tools, and two to three cubes from the outer wall of the block.
4. Pulling cubes from the top
Grab a cube by its top face and pull, and it tears halfway, leaving a ragged step. Instead, press the whole block down and lift the cube from its base with a slight twist, working from the inside of the cavity outward. The scoring is deepest near the surface and shallowest at the bottom, which is why the last few millimetres need the twist rather than a tug.
5. Removing the full depth for a flat object
A tablet or a thin instrument does not need a cavity down to the base layer. Pull the top layer of cubes only, or split the block horizontally with a long knife and pull from the upper half. Leaving foam under the object is what absorbs the shock; a thin item lying on the hard base layer is worse off than it was in the bag.
6. Forgetting the finger cut-outs
An item that fits snugly, as it should, cannot be lifted out without a notch for your fingers. Pull one or two extra cubes on the long side of each cavity as a finger hold. Every professional CNC layout has them; most first-time pick-and-pluck jobs do not.
7. Cutting for the kit as it is today
Every kit grows. Leave one or two uncut rectangles somewhere in the block for the next lens, the spare battery, the cable you keep forgetting. A blank area costs nothing now and saves a new foam set later. The same rule applies to tool kits, camera kits and drones alike, and it applies here twice as hard.
8. Trying to glue cubes back
It never works. Glue stiffens the foam, the joint fails, and the cube ends up loose in the case with your equipment. If a cavity is too large, the honest fixes are a strip of separate foam wedged in, a new pick-and-pluck block, or a CNC set. A replacement foam set is cheap compared with the case, which is why we stock them for most models.
9. Ignoring the lid foam
The egg-crate lid foam is not decoration. It presses on the equipment from above and stops it lifting out of its cavity when the case is upside down. If your items stand higher than the block, the lid foam gets crushed and eventually torn. Either cut deeper, or accept that the tallest items need their own cavity in the base layer as well.
10. Using pick-and-pluck where it was never going to hold
A 4 kg telephoto lens. A tool kit that goes in and out thirty times a day. A drone with arms that bear on the foam walls at every insertion. Polyurethane cubes will hold these for a while, then walls start to tear and the layout drifts. That is the signal to move to CNC-cut foam, which is covered further down.
Replacement pick-and-pluck foam sets for a fresh start
Part 3: How to cut it properly, step by step
Tools
A long, thin, very sharp knife for splitting layers (a bread knife with fine serrations works; a box cutter does not). A marker. Toothpicks or pins to mark cavity corners. A flat table. Nothing else.
The method
Lay the items out with the spacing from mistakes 2 and 3. Push a pin into the foam at each corner of each cavity, one cube inside the object's outline. Remove the items. Press the block flat with one hand and, with the other, lift the first cube from the centre of the cavity by its base, twisting slightly. Work outward to the pins. Pull the finger notch last. Test-fit the item; if it drops in without resistance, you have removed one cube too many on one side, and that is why you started from the centre. Repeat for every cavity, then put the base and lid layers back and close the case on the full kit to check the lid foam is not crushed.
Keep the cubes
Not to glue them back. To fill a cavity temporarily if a piece of equipment is out for service, so the rest of the kit does not shift.
Two-layer cutting for mixed-height kits
Most kits mix tall and flat items: a camera body next to filters, a multimeter next to test leads. Rather than cutting everything to full depth, split the pick-and-pluck block into an upper and a lower half with the long knife before you start. Cut cavities for flat items in the upper half only. Cut cavities for tall items through both halves. Reassemble with the lower half underneath. The flat items now sit on a full layer of foam instead of the thin base, and the tall items are held along their whole height. It takes an extra ten minutes and roughly doubles the protection for the flat items.
Marking the foam so the layout survives
Once the layout is finished, photograph it with the equipment in place and tape the photo inside the lid or keep it with the kit list. When an item is replaced by a newer model, the photo shows which cavity to adapt. It also lets a colleague repack the case correctly without guessing, which is the difference between a case that protects and a case that holds.
Part 4: Foam materials, densities and what they mean for your kit
Polyurethane (PU): the pick-and-pluck material
Open-cell polyurethane is soft, light and cheap, and it is what almost every pre-scored block is made of. Its density is typically in the 20 to 30 kg per cubic metre range. It cushions well against light impacts and vibration, absorbs water if it gets wet, compresses permanently under sustained load, and yellows with age and UV. It is the right material for cameras, instruments and electronics under about 2 kg per item, opened a few times a week.
Polyethylene (PE): the CNC material
Closed-cell polyethylene is firmer, heavier and considerably more expensive per block, with densities from around 30 kg per cubic metre for softer grades to 45 and above for hard-wearing inserts. It does not absorb water, can be wiped clean, does not crumble, and holds a cut edge for years. It is what professional inserts for firearms, tools, medical kits and heavy optics are cut from. It cannot be plucked; it has to be cut or machined.
Cross-linked polyethylene and EVA
Cross-linked PE has a finer cell structure and a smoother surface, which suits presentation cases and anything where the foam is visible to a customer. EVA is a related material with a slightly rubbery feel, used where a softer grip is wanted on delicate finishes. Both are CNC materials, not pick-and-pluck.
Convoluted (egg-crate) lid foam
The lid layer is a thin PU sheet cut into peaks and valleys. The shape lets it compress a long way without much force, which is why it can press down on items of different heights at once. It is the first layer to wear out in a hard-working case and the cheapest to replace; most replacement sets include it.
Anti-static and conductive foams
Electronics assemblies, PCBs and sensitive instruments sometimes need foam that does not build a static charge. Anti-static PU and conductive PE exist, usually in pink or black, and are specified by surface resistance. If your kit has exposed boards or connectors, ask for it; standard pick-and-pluck is not anti-static.
How to match foam to load
A rough rule for a first estimate: light items (under 1 kg) and low frequency of use, standard PU pick-and-pluck. Medium items (1 to 2 kg) or daily use, higher-density PU or soft PE. Heavy items (over 2 kg), sharp edges, firearms, or kits that must look the same after five years, closed-cell PE cut on CNC. The foam should always be the softest material that still holds the item without deforming, because softer foam absorbs more shock.
Part 5: Layouts that work, by profession
Photographers and videographers
Body in the centre with a lens attached, standing on its base; lenses around it standing upright with the mount down and a cap on; batteries in one row along an edge, contacts protected; cards and filters in a shallow upper-layer pocket. Leave a cavity for the next lens. Most photographers outgrow pick-and-pluck quickly and move to padded dividers or TrekPak, which we compared in foam, dividers or TrekPak.
Drone pilots
Drone in the centre with arms folded, propellers off; controller in its own cavity with the sticks protected by a shallow upper-layer pocket; batteries in a row with at least two cubes between each, because a swollen cell must have room; charger and cables in a corner. Never cut a cavity so tight that inserting the drone flexes its arms against the foam walls; that is the fastest way to tear the layout.
Field technicians and engineers
Instruments (meter, camera, tester) in the deep layer; probes, leads and adapters in the upper layer directly above the instrument they belong to; consumables in a single open cavity. A printed inventory in the lid. This is the kit that most often needs to move to CNC within a year, simply because it is opened so often.
Firearms and optics
Pick-and-pluck is a temporary solution here at best. Firearms are heavy, have hard edges, and are inserted and removed with force. Use it to test a layout for a few weeks, then have the layout cut in closed-cell PE with recessed finger holds and cavities for magazines and optics.
Medical and first-response kits
Speed of access beats snugness. Larger finger notches, wider cavities and colour-coded foam layers help someone find the right item in the dark. Anything that must not be contaminated needs closed-cell foam that can be wiped; open-cell PU in a medical case is a hygiene problem waiting to happen.
Part 6: When to stop and order CNC foam
The kit is fixed and valuable
If the contents will not change for a year and are worth more than the case, CNC foam pays for itself. The cavities are cut to the object's real shape, with a tolerance that grips without crushing, in closed-cell foam that does not tear or absorb moisture.
The kit is heavy
Polyurethane pick-and-pluck holds light and medium items. Above roughly 2 kg per item, or for items with sharp edges or protruding arms, the cube walls fail. CNC-cut polyethylene holds the weight and keeps its shape.
The kit is opened many times a day
Every insertion wears the foam. A demo kit, a tool kit, a calibration set that is used on every job needs the harder material.
You need more than one identical case
Two hand-cut layouts are never identical. A CNC file produces the same interior ten or a hundred times, which matters for teams that swap kits, and for procurement that wants a repeatable specification.
The object needs a shape, not a rectangle
A pistol grip, a camera body with a lens attached, a sensor with a cable tail. Pick-and-pluck cuts rectangles. CNC cuts the shape, including recessed finger holds, stepped depths, and cavities for accessories inside the main cavity.
What a CNC order needs from you
A photo of the equipment laid out on a table with a ruler in the frame, or the item list with model numbers. We design the layout, send a drawing to approve, and cut the foam. The foam arrives fitted in the case. Examples of what that looks like are in custom foam inserts in Peli cases.
What a CNC insert costs, roughly
Less than people expect for a single case and far less per case for a run of identical ones, because the design work is done once. The design is the expensive part; the machining is minutes. If you are on the fence, ask for a quote with the drawing; you can see the layout before you commit to anything.
What CNC-cut foam looks like in practice
Frequently asked questions
Can I buy a new pick-and-pluck block if I ruin the first one?
Yes. Replacement foam sets exist for almost every Peli Protector and Air model, sold as a full set of lid, pick-and-pluck and base layers. They are the cheapest way to start again.
Is pick-and-pluck foam waterproof?
No. It is open-cell polyurethane and will absorb water if the case is opened wet. The case keeps water out; the foam does not. CNC inserts are usually closed-cell polyethylene, which does not absorb water and can be wiped dry.
How long does pick-and-pluck foam last?
Years, if the layout is cut with margins and the items are light. Months, if the walls are one cube thick and the kit goes in and out daily. Yellowing is normal and cosmetic; crumbling or tearing means it is time to replace.
Can CNC foam be cut for a kit that changes?
Partly. A good layout leaves spare cavities and uses a modular grid so that one insert can be replaced without recutting the whole set. If the kit changes every week, dividers are the better answer and CNC is not.
Can I cut pick-and-pluck foam with a hot wire or electric knife?
An electric carving knife works well for splitting layers and trimming. A hot wire melts polyurethane into a hard, glassy edge and releases fumes; do not use it indoors and do not use it on the pre-scored block at all.
Does foam damage equipment over time?
Old polyurethane can become sticky as it degrades and leave residue on rubber grips and painted surfaces. If the foam feels tacky, replace it. Closed-cell PE does not do this.
Checklist before you pull the first cube
- ✅ Everything laid out on the foam, photographed, corners marked with pins
- ✅ Each cavity one cube smaller than the object on every side
- ✅ Two cubes between cavities, three around heavy items, two to three from the wall
- ✅ Finger notch on every cavity
- ✅ Depth matched to the object; thin items on the upper layer only
- ✅ One blank rectangle left for the future
- ✅ Lid foam still uncrushed when the case is closed on the full kit
- ✅ Item over 2 kg, sharp-edged, or used daily? Skip the cubes and order CNC
The short version
Pick-and-pluck foam is fine for a light, stable kit if you plan the layout, cut small, leave walls, and pull from the base. It is the wrong tool for heavy, sharp or hard-working kits, and no amount of care fixes that. When the cubes start to tear, do not glue: order a fresh set or, if the kit has earned it, a CNC insert cut to the shape of the equipment. 🧰
Send us a photo of your kit on a table with a ruler in the frame, and we will tell you honestly whether pick-and-pluck will hold it or whether CNC is worth it.
