Casting Molds for Patio Pavers, etc.

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Project by GnarlyErik posted 10-05-2012 07:46 PM 5427 views 12 times favorited 6 comments Add to Favorites Watch

I like working in my shop and my wife enjoys working in our yard. She recently decided to expand our patio by casting her own concrete pavers. We bought some plastic molds at Lowes, but they seemed a bit limited, so she asked me to make custom ones for fitting in odd places.

Using 2×4 stock to match the thickness of the plastic molds, I’ve made irregularly shaped molds for our pavers. When direct casting into a mold you must allow for getting your piece out of the mold. The usual way is to build ‘draft’ into the mold, and you do this by tapering the sides about 5 degrees or more so the casting comes out the wider side and does not bind to the mold.

In this instance, acrylic caulking was used for filleting material at the join between the sides and the bottom (which becomes the ‘top’ of the finished casting). Then, using a heavy latex paint the bare wood was coated. When that dried, a spray-on bed-liner type rubber coating was applied. Concrete likes to bind and stick to things, so a mold release agent must be used. For concrete, spray on Pam works well, or kitchen vegetable oils, diesel fuel or almost any oily liquid.

If you want to decorate your casting, it is easy to use a quick hardening acrylic caulk to make a design, pattern, or even a name – much as in cake decorating. Modeling clay and many other materials work well too. You must make your design ‘reversed’ or a mirror image for it to come out as intended. Acrylic caulk may be scraped off your mold, and a new design easily applied. Simple molds may be made for casting in many mediums other than concrete such as plaster, thickened epoxy, body filler putty, fiberglass, etc. Many mediums cure through an ‘exothermic reaction’ wherein the mixing of the materials produces its own internal heat. This is why concrete may be poured in cold weather. Some mediums like fiberglass and epoxy can produce lots of heat – and even catch fire.

If you decide to try casting, research your medium well before attempting your casting!

-- "Never let your dogma be run over by your karma!"

6 comments so far

View Jim Jakosh's profile

Jim Jakosh

27794 posts in 4595 days

#1 posted 10-06-2012 02:00 AM

Very ingenious! Great idea!!.................Jim

-- Jim Jakosh.....Practical Wood Products...........Learn something new every day!! Variety is the Spice of Life!!

View MarkTheFiddler's profile


2068 posts in 3678 days

#2 posted 10-06-2012 02:06 AM

Eric, I never would have thought of it! Favorite for future reference. Thanks for sharing.

-- Thanks for all the lessons!

View Juriathe's profile


143 posts in 4008 days

#3 posted 10-06-2012 03:04 AM

I experimented with making my own patio square pavers last summer but I just used rubbermaid storage containers. It worked well, but I discovered .. painfully .. that while the rubbermaid surface gave a beautifully smooth finished top, it was EXTREMELY slippery when wet. I like the rough-looking texture your’s has, Eric. I’m sure it’s much safer than mine were. I do like the shapes, too. Thanks for sharing; I fully intend to try your method.

-- I'm so busy I don't know if I found a rope or lost a horse...

View lightweightladylefty's profile


3672 posts in 5202 days

#4 posted 10-06-2012 04:04 AM


Thanks for sharing the details of how to do these. My husband has been talking about this and now we have more specifics. Thanks.


-- Voltaire: “Those Who Can Make You Believe Absurdities, Can Make You Commit Atrocities” There are 112 genders (not including male and female)

View Bluepine38's profile


3393 posts in 4575 days

#5 posted 10-06-2012 02:13 PM

Great idea, thank you for sharing. Do you have any pictures of the finished patio to share?

-- As ever, Gus-the 83 yr young apprentice carpenter

View GnarlyErik's profile


367 posts in 3624 days

#6 posted 10-07-2012 12:39 AM

We are just beginning the process of casting the pavers. Will post pictures when done – loosely forecast to expect in about a month or so.

-- "Never let your dogma be run over by your karma!"

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