What should I bring to a first Case Showroom visit?

Answer: A tape, a caliper, a feeler gauge, radius gauges, a 0.1 g scale and a score sheet.

Which seam gets missed most?

Answer: The rim step. Half-close to a 5 mm gap and push sideways; a shallow step shifts 2 mm and the latch goes off centre.

Why not compare weight by hand?

Answer: A hand reads absolute mass, and mass only means something against size.

Can wall thickness be measured on site?

Answer: Not with a caliper, since the rim is double-layered. Weighing and dividing by area holds within 0.2 mm.

Should the weights stay the same?

Answer: No. Air freight lifts hardware to 25 percent, stacking lifts wall to 30 percent, indoor display can skip sealing.

Will the unit I liked change in production?

Answer: Mostly in colour and hardware batches. Keep a signed reference unit and photograph the readings.

Skip the Hand Feel: Judging a Case Showroom by Three Seams

Quick answer: Judging weight by hand and colour by eye is the fastest way to buy wrong in a Case Showroom, because a hand has no reference and showroom light rewrites colour. Three seams, one weighing and one latch count replace both.

Why Hand Feel Misleads in a Case Showroom
Seam One: Parting-Line Offset
Seams Two and Three: Flash, Mould Line, Rim Step
One Weighing: Wall Thickness From Weight
Turning Measurements Into a Score
FAQ

1. Why Hand Feel Misleads in a Case Showroom

Hand feel is relative and has no reference point. Lift ten units in a row and the second reading is anchored by the first: after a 1.8 kg case, a 2.4 kg one feels absurdly heavy.

Temperature rewrites the reading too: at 22 °C a PP latch feels crisp, in a 5 °C warehouse it needs two hands.

Gut reading	Distorted by	Substitute	Pass mark
Feels heavy	Size, inserts	Weigh, divide by area	Within 8%
Feels stiff	Room temperature	Thumb-press the wall	Recovers in 1 s
Colour looks right	Colour temperature	ΔE against a card	3 or less
Lid closes tight	Latch travel	20 cycles, measure	2 to 4 mm
Seam looks fine	Light angle	Feeler gauge	0.3 mm or less

A 400 mm and a 600 mm case at the same 3 mm wall differ by over 40 percent in mass; a hand only reports "heavier".

Hand feel can rank units in a Case Showroom. It cannot set a size step.

2. Seam One: Parting-Line Offset

The parting line is where the two mould halves meet, leaving a ring around the wall. One criterion applies: offset. Drag a fingernail across it; a clear step means 0.5 mm. With a feeler gauge, 0.3 mm passes and 0.5 mm concentrates stress under stacking.

Case Showroom: a blue case lying flat and tilted left, the ring seam around the side wall, two hinge seats at the handle root

Read four corners and four edge midpoints, then take the maximum; a single reading is fooled by light, since a 0.4 mm step lit from the front looks like zero.

Offset comes from worn locating pins, which drift past 0.1 mm clearance. A new tool holds 0.1 mm; rotomoulded cases tolerate 0.6 mm because the tool carries a 1.5 mm parting platform, but flash there must be trimmed flat.

3. Seams Two and Three: Flash, Mould Line, Rim Step

Read the last two seams together and you are reading tool health: when clearance opens, all three degrade at once.

Mould line: 0.15 mm or less on injection mouldings, 0.4 mm on rotomoulded parts
Flash: 0.2 mm or less at the rim; a trimmed mark is a worse stress riser than the flash
Rim step: 1.5 mm of overlap or more; below 1 mm a sideways push shifts the lid
Interior radius: R3 or larger, since an R1 corner cuts foam and cracks first
Rib root: a 0.5 mm fillet, or it cracks at three times the rate

The rim step is what buyers skip. Half-close the lid to a 5 mm gap, push sideways, and a shallow step shifts by 2 mm while the latch goes off centre.

4. One Weighing: Wall Thickness From Weight

Bring a 0.1 g scale with a 5 kg capacity and leave the caliper in the bag. Weigh the empty unit, measure outside dimensions, divide mass by area; two units in one series should land within 8 percent.

Case Showroom: a bright green case lying flat and tilted thirty degrees, four lid ribs joined to the long side ribs, matching foot pads

Two figures that reconcile: a case with a 400 by 300 by 150 mm interior at a 3.0 mm wall weighs about 1.8 kg; the rotomoulded equivalent at 4.0 mm weighs 3.2 kg. That gap comes from process.

A caliper fails here: the rim is two layers stacked and the wall carries draft. Mass over area over density gives mean wall thickness within 0.2 mm. A 25 kg rating on 1.8 kg is a ratio of 14; below 8 the body bulges at the second tier.

5. Turning Measurements Into a Score

A Case Showroom visit only argues productively once five criteria share one scale. Weight them, score each, cut anything under 70 before sampling.

Item	Weight	Method on site	Cut-off
Interior size and radius	30%	Tape at three points	Off by 2 mm
Wall and mass ratio	25%	Weigh, back-calculate	Spread over 8%
Hardware and cycles	20%	20 cycles, measure travel	Under 2 mm or over 4 mm
Sealing	15%	Paper pull, 3 minutes of spray	Damp paper
Appearance and colour	10%	ΔE against a card	ΔE above 3

Weights move with the job: air freight lifts hardware to 25 percent, three-tier storage lifts wall to 30 percent. Recalculate after any change.

Conclusion

Selecting in a Case Showroom is not a matter of eye and hand but of a routine that runs in ten minutes: eight offset readings, three seams, one weighing, twenty latch cycles. Fix the criteria and ten units on one floor become comparable. Bring a colleague back with the same sheet, and a Case Showroom produces numbers instead of impressions.

This article discusses only the container (case body) side of specifications and design intent, and does not cover any handling, loading or use of the contents.