Stone Master Molds Rubber Molds for Concrete, River Rock 1-Step-Corner Mold

Stone Master Molds Rubber Molds for Concrete, River Rock 1-Step-Corner Mold


  • Each 1-step corner mold includes a corner plug for quick production
  • Professional grade rubber mold lasts for hundreds of pours
  • Each of 3 mold versions has one-of-a-kind stones
  • Matching River Rock flat molds also available
  • NO RELEASE AGENT necessary
  • Made in the USA
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2 - 3



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7 - 99


Stone Master Molds River Rock Corner Mold

Stone Masters' River Rock corner molds duplicate a naturally river-worn, full-size stone, varying in sizes up to 10” in diameter, with thickness varying from 1-2.5" in the center.  River Rock is most often used on log cabins and coastal homes, on the outside and inside, not to mention it is gorgeous on fireplaces, too.

Our River Rock corner molds create stones that are up to 8 inches in diameter and vary in thickness from 1-2.5 inches at the center. Each mold makes approximately 1 linear foot with a grout joint.  In addition, each mold measures approximately 12" long by 12" wide, by 4.25" thick.

Each 1-step corner mold includes a specially designed corner plug for quick production at no extra cost. 1-step corners allow you to pour the corners in one step: Pour the long, horizontal end first, place the plug on the mold, then fill the open, short end and lightly vibrate. Matching River Rock flat  molds are also available.

Of great importance, our molds require NO release agent!   Save money, time, and clean up, as well as gaining an easy, clean release of face color pigments, unlike plastic molds, urethane molds, and silicone molds.

Available in 3 unique variations, with no stone repeats.  Also, matching River Rock flat molds are available.

Made in the USA, both materials and labor.

Manufactured Stone Basic Mixing Procedures Using A Pre-bagged Concrete Mix for your River Rock molds:

This is one suggestion for mixing the concrete for the River Rock molds. There are many other instructions available online, including videos.

BE SURE TO USE A CONCRETE MIX THAT CONTAINS PORTLAND CEMENT. We recommend Sakrete Maximizer, as it has lightweight aggregate, is high strength, and yields more product, but there are many kinds you can use. Follow the manufacturer’s instructions for mixing.

If using pigment, add desired iron oxide pigment to mixer (100% pure, no additives). These can easily be found on Amazon, etc.

A plasticizer can be added to reduce the amount of water in the mix. Pour into the molds which may already have coloring additives… NO RELEASE AGENT NECESSARY. Vibrate molds to release air bubble.

Finally, cure the concrete in the River Rock molds for approximately 24 hours at the minimum of 70 degrees Fahrenheit before demolding. Higher humidity is desired. Molds can be covered with a tarp to retain more heat and humidity. Continue to cure demolded stones at 70 degrees or greater until ready.


3 reviews for Stone Master Molds Rubber Molds for Concrete, River Rock 1-Step-Corner Mold

  1. RC

    Robert C.

    They have very good quality molds will be buying more soon thanks guys!

  2. AC

    Amazon Customer

    Makes nice rocks for the money

  3. LS

    Love Stone Arts

    These are just as described and I am completely satisfied with all three corner river rock molds. I’ve purchased and salvaged several lots of faux river rock veneer but I am short on corners for the tapered columns that I am currently facing. It’s exciting to cast my own corner stones for the first time. I wondered if they would actually come out of the molds properly without the use of a mold release agent. Yes they do! I’m experimenting with various small aggregate cement mixtures and so far they have all produced a strong and great looking corner stone.

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