240 Bullion Displays — and the 0.3 mm That Separates a Smooth Slide Base from a Loose One

The Challenge

How close do you let a customer get to a 10 oz gold bar? At current metal prices, that question is the whole floor plan of a bullion shop. Too far — bars behind glass at the back wall — and the product loses the tactile pull that closes precious-metals sales. Too close — bars loose on an open tray — and the counter becomes a grab risk that staff manage with their nerves.

The dealer's existing middle ground was failing on both ends. Their counter cases had lift-off lids: showing a bar meant lifting the whole lid with two hands, finding somewhere on a glass counter to set it down without scratching either surface, and leaving the entire case open at customer arm's reach for the length of the conversation. A few generic slide boxes they had tried were worse — the panels either jammed halfway or slid so freely that a case picked up at the wrong angle started opening itself. For the new fit-out they wanted one specific behavior, described in one sentence in their inquiry: a case that opens in one smooth motion for staff and does not open at all for anyone else. Alongside the bar cases, they needed counter blocks for encapsulated 1 oz silver rounds — simpler pieces, but sized to the actual capsules, not to a nominal coin diameter.

Our Approach

"Smooth but never loose" is not a drawing dimension — it is a feel. So we treated the slide fit as the project's central engineering question and built the sampling step around it, then let the rest of the case follow from how bullion actually sits on a counter.

Tuning the slide: three tracks, one winner

The base panel runs in a track milled directly into the case's side walls. Clearance between panel and track decides everything: too tight and the slide binds; too generous and the base drifts. For the sample we cut the same case with three per-side clearances — 0.2 mm, 0.3 mm, and 0.45 mm — and put them through hand tests rather than debating tolerances on paper. The 0.2 mm track ran smoothly out of the box and bound up the moment fine dust worked into the groove. The 0.45 mm track never jammed but rattled, and when we tilted the loaded case the base crept open on its own. The 0.3 mm track slid with one finger, held its position at rest, and stayed seated when the case was lifted and carried across the room. That was the number that went to production.

The second safeguard is mechanical, not tolerancing: a small acrylic end stop bonded inside the track halts the base at roughly four-fifths of its travel. Staff can present the full row of bars, but the panel has to be lifted slightly over the stop to come completely free — a deliberate two-part motion, so no combination of tilt, bump, or hurry can put a loaded base on the floor. A finger recess milled under the base's front edge replaces a protruding handle that would snag.

Closed to the customer, open to the staff

Orientation did the security work. The track exits on one side only — the staff side of the counter — while the front, top, and customer-facing faces are fully bonded panels. A customer can lean in to read the hallmark on a bar from centimeters away; withdrawing anything requires standing where staff stand. Inside, the bars sit in angled channels lined with charcoal felt, which protects the mirror finish of a minted bar and stops the metal-on-acrylic rattle that makes a case feel flimsy. The format follows the same logic as the bar racks and lockable counter cases on our coin and bullion display cases page — this project simply moved the opening to a slide base and tuned it.

Weight set the material spec. A 10 oz bar is a dense little object, and a row of them will flex a thin base until the channels lose their grip — so the slide base runs 8 mm, the walls 5 mm. The channel geometry was fit-tested the same way the slide was: the dealer mailed two of their actual bars — a 1 oz at roughly 24 × 41 mm and a 10 oz — and the sample channels were cut to those pieces, not to a catalog dimension.

The second SKU: capsule blocks for silver rounds

The 90 capsule blocks were geometrically simpler but lived or died on the same discipline: a real object in hand before cutting. Each block carries rows of circular recesses machined to 40 mm capsule outside diameter plus about 1 mm, so an encapsulated 1 oz silver round seats flat, sits flush, and lifts out without prying. The dealer's capsules came from their existing inventory; one sample capsule mailed to us settled the recess dimension in a day. Displaying capsules flat in a block rather than loose in a tray also solves a small daily problem every bullion counter knows — round objects roll, and a block of seated capsules reads as a curated collection instead of loose change. Buyers weighing formats for slabs, capsules, and bars side by side can start with our coin display ideas guide, which maps each holder type to the display geometry it needs.

The Results

All 240 pieces shipped from an 18-day production run with zero rejects at pre-shipment inspection — and on this order, inspection meant motion, not just surfaces: every slide track was hand-cycled before packing.

The metric this dealer actually cared about never appears on a spec sheet: whether staff would use the cases correctly under pressure. A security feature that adds friction gets bypassed — lids left off, cases left open. Because the slide opens in one smooth motion and closes with a push, there is no temptation to leave it open between customers; the path of least resistance and the secure behavior are the same behavior. That is what the 0.3 mm bought.

The follow-on order arrived before the season ended: a second batch for the dealer's other location, this time with the shop's mark laser-engraved on the case fronts — a frosted-white engraving in the acrylic itself, cut from the same files already on record from this run.

What This Means for Your Project

If your display has a moving part — a slide base, a sliding lid, a hinged door — the specification that matters is not "sliding base: yes" on a quote sheet. It is the clearance number, and the only honest way to pick it is the way this order did: multiple sample fits, tested by the hands that will use them, with a mechanical stop backing up the tolerance. Ask any fabricator quoting you a sliding mechanism what clearance they cut and how they validated it; a shrug is a rattle you will hear later.

And if the display holds real value — bullion, watches, graded rarities — think in terms of asymmetric access: which side opens, who stands there, and what the lazy behavior defaults to. Geometry enforces policy better than staff training does. A 50-piece MOQ per design puts this kind of purpose-built case within reach of a single-location dealer, not just a chain.

Common Questions

How do you make an acrylic slide base glide smoothly without sliding open on its own?

Track clearance decides both behaviors, so we tune it by hand instead of trusting the drawing. On this order we cut three sample tracks at 0.2, 0.3, and 0.45 mm per-side clearance: the 0.2 mm track bound up as soon as any dust entered the groove, the 0.45 mm track rattled and let the base drift when the case tilted, and 0.3 mm slid with one finger yet stayed seated when the case was picked up and carried. A bonded end stop adds the safety layer — the base halts at about four-fifths of its travel and has to be lifted slightly to come fully free, so it cannot slide out unintentionally.

What acrylic thickness does a gold bar display need?

Match the gauge to the metal's weight. These cases ran 5 mm walls with an 8 mm slide base, because the base is the loaded part — a row of 10 oz bars will flex a thin panel and the channels lose their grip. Small formats holding only 1 oz bars can run lighter, and kilo bars push the requirement further: a deep channel, heavier gauge, and a wide rest base. We confirm gauge during sample approval against the actual bar sizes going in.

Will the capsule blocks fit Air-Tite and similar coin capsules?

Yes — each recess is machined to the capsule's outside diameter plus about 1 mm, so the capsule seats flat and lifts out without forcing. This order used 40 mm recesses for encapsulated 1 oz silver rounds; 39, 32, and 27 mm are the other common diameters. The reliable route is to mail us one of your actual capsules — we measure it, cut a sample recess, and verify the fit before production, the same way we fit-test bar channels against real bars.