Perth Mint Box – Custom Holder for 1oz Britannia Silver Coins (3D Printed Insert)

3D-Printed Insert – Functional Design Overview

The internal insert has been purpose-built using 3D printing to convert a standard Perth Mint coin box—originally designed for smaller denominations—into a precision holder for 1oz Britannia silver coin coins.

Design Intent & Fitment
The insert is dimensioned to match the internal cavity of the box with tight tolerances, ensuring a friction-fit installation without the need for adhesives. This prevents internal movement while preserving the original structure of the box.

Each coin slot is engineered to match the diameter (~38.6mm) and thickness profile of a 1oz Britannia coin, allowing coins to sit flush within the cavity. The depth is calibrated so coins are recessed slightly below the top surface, reducing the risk of contact with the lid and minimizing surface abrasion.

Material & Structural Properties
The insert is manufactured using a rigid thermoplastic (commonly PLA or PETG), providing:

• Sufficient compressive strength to maintain shape under load
• Dimensional stability over time
• Low warping to ensure consistent slot geometry

Layer resolution from the print process creates micro-texturing, which subtly increases grip and reduces coin slippage without damaging edges.

Retention & Protection Mechanism

• Friction-based retention: Each cavity applies light lateral pressure to keep coins stable
• Edge support geometry: Coins are supported along their rim rather than flat surfaces, reducing contact with detailed faces
• Shock distribution: The insert absorbs minor impacts and prevents coins from knocking into each other during handling or transport

Modular Conversion Functionality
This insert effectively repurposes the original box:

• Converts multi-coin small-denomination storage into a 1oz format
• Maintains original external aesthetics while upgrading internal capacity
• Allows reversible modification (insert can be removed if needed)

User Interaction & Practicality
Coins can be easily inserted and removed without excessive force due to optimized tolerances. The layout ensures:

• Clear visibility of each coin
• Quick access for handling or display
• Secure placement for transport or stacking