If you want to cast a full, matching set of drink coasters in one sitting - not a mismatched pile of singles - the Zenlogy 10-piece silicone coaster mold set is built for exactly that job. Inside the box are four round molds, four square molds, and two coaster-holder molds, all sized to the standard ~4 in (10 cm) drink-coaster footprint. The short version of this review: it is a complete, beginner-friendly system for clean, flat-back, high-clarity coasters, and its one real limitation is depth. At roughly 0.39 in (1 cm) of cavity, these are single-shallow-pour molds, not deep-river or thick-bezel molds. If that matches what you want to make, it is an easy recommendation. If you are dreaming of chunky cast edges, you should size up - and we will say exactly when, below.
For broader context on how this slots into a resin maker’s toolkit, see our resin equipment reviews hub, which collects molds, mixers, and curing gear in one place.
What’s in the box and how the pieces work together
The 10-piece count breaks down as 4 round coaster molds + 4 square coaster molds + 2 coaster-holder (caddy) molds. That mix is the set’s whole reason to exist: you can pour eight matching coasters and a holder to keep them in, all from one purchase, without hunting down a separate caddy mold later. The full configuration is laid out in the specs below.
Both coaster shapes share the same nominal ~4 in (10 cm) footprint, which is the standard drink-coaster size. That size matters for two practical reasons. First, a 4-inch coaster comfortably sits under common pint glasses, mugs, and tumblers. Second, off-the-shelf cork or felt backing pads are widely sold in a 4 in / 10 cm round and square - so when you want to add a non-slip, non-scratch backing to a finished coaster, the parts just fit. You are not stuck trimming oversized cork to an oddball diameter.
The two holder molds are the one place the set asks you to plan. Two holders is enough for a single caddy, or one round-coaster caddy and one square-coaster caddy. If you want a dedicated holder for every style, you simply run the holder molds again in a second batch. That is a minor workflow note, not a flaw - but it is worth knowing before you mix resin so you are not surprised when only two holder cavities are present.
Build quality and why the mirror finish matters
Two construction details drive the quality of what comes out: the wall thickness and the interior finish.
The walls are reinforced silicone at approximately 0.12 in (3 mm). On a thin, wide mold that reinforcement does real work. A floppy-walled coaster mold tends to bow or splay outward under the weight of a full resin pour, and the cured coaster inherits that distortion - an oval instead of a circle, or a square with a belly in one side. Stiffer walls hold the shape so the coaster cures round-and-true or square-and-true, and stays flat rather than potato-chipping.
The interior is glossy and mirror-smooth, and this is the feature that most affects your finished result. Resin takes on the exact texture of whatever surface it cures against. Because the underside of the mold is a mirror, the face of the coaster that sits in the mold cures to a high-clarity, glass-smooth finish with no sanding and no polishing - provided the resin is mixed and cured correctly. That is a genuine time-saver: hand-polishing a clear coaster to optical clarity is tedious, and this mold lets you skip it.
The trade-off of a mirror is that it is unforgiving of contamination. Every speck of dust or lint that lands in the cavity, or rides in on the resin, telegraphs straight into that clear face. We cover keeping the surface clean in the care section, but the headline is simple: protect the gloss and it rewards you; neglect it and the flaw shows.
The spec that actually matters: depth versus resin volume
The single most important number on this mold is the cavity depth, listed in the specs below at approximately 0.39 in (1 cm). Everything about how you use it flows from that one figure.
Depth dictates resin volume, and the volume figures are the difference between a clean single pour and a frustrating guess. Budget roughly 40 ml per round coaster at a shallow 5 mm fill, or about 60 g per round coaster and 75 g per square coaster when you fill the full ~1 cm rim. Squares hold more than rounds simply because a square encloses more area than a circle of the same width.
To fill all eight coaster cavities in one batch, mix roughly 520-600 g (about 18-21 oz) of combined resin and hardener. Always mix a little extra. Coming up short mid-pour forces you to mix a fresh batch and pour it onto resin that has already started to gel, which can leave a visible cold-joint line in the clear. A small amount left over is the cheap, safe outcome.
If you also plan to pour the two holder molds in the same session, add resin for those on top of the coaster total - check the holder cavity depth on your specific listing, since holder geometry varies more than the coaster cavities do.
Single-pour workflow: one pass, no layering
Because the cavity is about 1 cm deep, you fill it in a single pass. That is the entire appeal of a shallow coaster mold, and it is also a safety margin.
Standard casting and tabletop epoxy resins are typically rated for pours up to roughly 0.5 in (about 12 mm) per layer. Beyond that, the chemical cure releases heat faster than a thick mass can shed it - the exotherm - and excess exotherm is what causes cracking, yellowing, and runaway bubbling in deep pours. A 1 cm coaster sits comfortably under that 12 mm per-layer threshold, so a single full-rim pour cures without thermal drama. This is exactly why this style of mold is friendly to beginners: the geometry keeps you inside the safe zone by default.
You only need to layer if you are doing it on purpose - building a suspended design with a clear base layer, then embeds, then a top layer - or if you are working with a thin UV resin that can only cure a few millimeters per pass. For a straightforward clear or pigmented coaster in standard epoxy, one pour is the whole job.
A brief, conservative safety note: resin and hardener are chemicals. Work in a ventilated space, wear nitrile gloves, and follow the exact mix ratio, working time, and cure schedule printed by your resin manufacturer - those instructions override any general numbers here, because exotherm behavior, safe pour depth, and cure times differ by product.
Troubleshooting on this specific mold
A few issues come up repeatedly with shallow open-top coaster molds, and all of them are process issues rather than mold defects.
Tacky or sticky backs. The molds are open-topped, so the exposed face - which becomes the coaster’s back - cures against air. The most common cause of a tacky back is oxygen inhibition (the air-facing surface cures more slowly) or an off-ratio, under-mixed batch. Measure by weight to the manufacturer’s ratio, mix the full stated time while scraping the sides and bottom of your cup, and cure warm (around 75 F / 24 C) and dry. To rescue a back that already cured tacky, wipe the uncured film with isopropyl alcohol and brush a thin flood coat of correctly mixed resin over it.
Concave or dished centers. Thin, wide coasters can pull inward slightly as epoxy shrinks on cure, leaving a faint dish in the middle. Overfill to a small domed meniscus above the rim so surface tension holds the extra resin, or add a thin second flood coat after the first gels. Confirm the bench is level with a small bubble level - an out-of-level surface reads as a tilted coaster face.
Bubbles and dust. Bubbles release with a quick pass of a heat gun or torch held well above the surface; dust is the mirror finish’s enemy, so keep the molds covered between pours. The relevant care steps follow.
Care, reuse, and protecting the surface
The high-clarity finish lives entirely in the mold’s mirror interior, so caring for the mold is caring for your results. Never use sharp tools, scouring pads, or solvents inside the cavity. Demold by flexing the flexible silicone from the back rather than prying at an edge, which protects both the coaster and the surface. Wash with mild soap and warm water, dry completely, and store the molds covered or in a sealed bag so dust and lint cannot settle into the gloss. If a cured-resin haze ever builds up, a wipe of mold release before the next pour restores a clean release without dulling the shine. Kept this way, the silicone is reusable for years and many castings.
Who should buy it - and who should size up
Buy the Zenlogy set if you want clean, flat-back, high-clarity drink coasters in standard 4-inch round and square sizes, and you like the idea of pouring a whole matching set plus a caddy from one box. For beginners, the shallow single-pour geometry and the no-polish finish remove two of the most common sources of frustration.
Size up to a 1-inch-deep coaster mold instead if you want chunky cast edges, deep embedded inclusions, or anything approaching river-style depth - the ~1 cm cavity here simply will not deliver that look. To weigh shallow versus deep molds and clear versus pigment-friendly options side by side, our best resin equipment buyers guide lays out the trade-offs, and you can browse every hands-on writeup from the reviews index.
See the comparison details, the full spec table, and the per-coaster resin numbers above to confirm this set matches the project you have in mind before you mix your first batch.