Blank Recessed Challenge Coins for UV Printing: What to Specify Before You Order
Why buyers order blank coins
Some buyers print their own designs on metal coins with a UV flatbed printer: small runs, personalised coins or fast-changing designs where a new die for every artwork would not make sense. They need a blank: a plated metal coin with a raised rim and a flat recessed area on one or both sides, and nothing else on it (no logo, no enamel, no engraving).
In October 2026 a US buyer who prints his own coins sent us exactly this request: a 50 mm round blank and a 50 × 50 mm square blank shown as a diamond, both about 3 mm thick, with a recessed print area on both sides, a reeded or diagonal-cut edge and four finishes. The points below are the ones that came up while preparing that quotation.
A typical blank specification
| Item | Example from a recent RFQ | What to decide |
|---|---|---|
| Outline and size | 50 mm round; 50 × 50 mm square displayed at 45° as a diamond | Exact outline; corner radius for squares (about 2 mm was requested) |
| Thickness | About 3 mm | Total thickness including the rim |
| Rim and recess | About 3 mm raised rim, about 0.4 mm recess depth, both sides | Printable area = outer size minus two rim widths (about 44 mm on a 50 mm coin) |
| Edge | Reeded or diagonal-cut; price also asked for a plain polished edge | Edge style per shape (see below) |
| Finish | Polished gold, polished silver/nickel, black nickel, antique bronze | Finishes and split per finish |
| Quantities | 100 / 250 / 500 / 1,000 / 2,500 / 5,000 per shape | First test order and repeat quantity |
| Packing | Economical bulk packing that prevents scratches; options for poly bags, sleeves and capsules | How the print face is protected in transit |
Stamped blank or die-cast zinc?
Stamped (die-struck) blanks are pressed from sheet metal such as iron. The strike leaves a dense, flat recess, which is what a UV printer needs, and the tooling for a simple round or square blank is relatively modest.
Die-cast zinc alloy is poured into a mould, so it can produce shapes stamping cannot: shields, Maltese crosses, stars, state outlines, cut-outs and areas of different thickness. The trade-off for printing is that a large flat recess on a casting can show small pores and needs more polishing before plating, and a thin UV ink layer shows every flaw underneath.
A practical approach is to use stamped blanks for the standard round and square shapes, and to review die-casting separately when a complex outline is needed. Our zinc alloy vs brass vs iron guide explains how the base metal is chosen for a design.
Rim width, recess depth and print area
The rim protects the printed area from scratches when coins are handled or stacked, and frames the artwork. A rim of about 3 mm with a recess of about 0.4 mm keeps the rim strong while leaving the largest practical print area. If you print white ink plus color plus a clear varnish, check that the total ink height stays below the rim. Keep the same rim width on round and square blanks if you want both to look like one product family.
Edges: round and square blanks differ
A reeded (milled) edge is rolled onto round coins after striking. Straight edges cannot be rolled the same way, so a square or diamond blank normally gets a plain polished edge or a texture formed in the die. If the two shapes must look alike, compare edge samples of both before ordering, and ask for the price difference between a reeded and a plain edge, because the extra edge operation is not free.
Plating and UV ink adhesion
Gold, silver, black nickel and antique bronze are electroplated finishes on the base metal. Each one prints differently: bright polished plating is very smooth, antique finishes are darkened and relieved, and some finishes receive a clear protective lacquer after plating. A lacquer layer changes how UV ink bonds, so ask whether one is applied and on which finishes.
- Clean the print area with isopropyl alcohol before printing.
- Use the adhesion promoter or primer recommended for your ink system, if any.
- Order samples of every finish and run a cross-hatch tape test with your own printer and ink before bulk.
- Ask which plating layers the coin has and whether nickel is present, if skin contact or nickel-free requirements matter to your buyers.
Packing that protects the print face
The recessed face is the product, so scratches matter more than on a finished coin. Bulk packing in layers with separators is the most economical; individual poly bags or sleeves add protection; coin capsules add the most. Ask for the per-piece cost of each option at your quantity.
Tooling, MOQ and timing
A custom blank needs one-time tooling, like any custom coin; unchanged reorders reuse it. A fully custom order can start at 10 pieces once the tooling fee is paid. A physical sample is normally made in about 7 days, production takes about 7 days after sample approval and courier delivery about 7 days; DDP delivery to the US and Europe can be reviewed for each route. See challenge coin mold fees explained for how tooling is quoted.
Frequently asked questions
Which base metal is best for a blank coin that will be UV printed?
For a flat recessed print area, a stamped (die-struck) blank usually gives the flattest, densest surface for UV ink. Die-cast zinc alloy is the better choice when later designs need cut-outs, shield or star outlines or different thicknesses, but large flat recesses on castings can show small pores and may need extra polishing.
How deep should the recess be and how wide the rim?
A common starting point is a raised rim of about 3 mm and a recess about 0.4 mm deep. On a 50 mm round blank that leaves a printable circle of about 44 mm. Ask for a dimensional drawing of the proposed blank and approve it before tooling.
Can a square or diamond-shaped blank have a reeded edge like a round coin?
Not in the same way. Reeded edges are rolled on round coins; straight edges cannot be rolled like that, so a square blank normally gets a plain polished edge or a texture formed in the die. Ask to see a sample of the edge before choosing.
Will UV ink stick to polished gold, nickel, black nickel or antique bronze plating?
Adhesion depends on your ink, primer and the exact surface, including any clear lacquer applied after plating. Clean with isopropyl alcohol, use an adhesion promoter if your ink system calls for it, and test-print one sample of every finish on your own printer before ordering in bulk.
How long does a custom blank order take?
A physical sample is normally made in about 7 days after the tooling fee is paid. After sample approval, production takes about 7 days and courier delivery about 7 days. Final timing depends on design, quantity, destination and customs.
Request a blank coin quote
Send the outline and size, thickness, rim and recess, edge style, finishes, quantities, packing and delivery postcode. Quote response within 24 hours.