Introduction: Concrete Lego Bricks

Awhile ago I watched a video of someone making candy lego bricks but they didnt interlock. I wanted to try the project and have the bricks interlock. I kept thinking about this project and ended up wanting to try it with concrete and not chocolate.

Step 1: Tools & Materials

1. silicone mix

2. concrete mix

3. sand paper

4. lego base plate

5. lego bricks

Step 2: Mixing the Silicone for the Mold

Picture of Mixing the Silicone for the Mold

I decided to make my own mold for this project so I could make various sizes of lego Bricks. My mold holds one pound of silicone which is 16 oz. so you need 8oz of part a and part b. I accidentally did 16oz of both. Next mix the two parts really well so you will get a correct casting. I poured the silicone mix as high as possible to get the bubbles out. After all the silicone was in i tapped the edges to get the air bubbles to the top.

Let the mix try for 24 hours. Once it was dry the legos came out very easily.

Step 3: Mixing the Concrete

Picture of Mixing the Concrete

I used quikrete 5000 but if I did this again I would use a countertop mix because this one had a lot of big rocks. I separated the big rocks from the mix with a sifter. I added water to the mix and tried to get an oatmeal texture. Next I scooped a little bit of concrete and pushed it down into the mold. I used my hand but you should use a popsicle stick to really push it into the mold

Make sure to vibrate the mold to get air bubbles to the top

I used a base plate to put in the back of the mold to try to add holes so the bricks would interlock. You will want to weigh it down with a heavy object.

Let it dry 24 hours

Step 4: Sanding the Blocks

Picture of Sanding the Blocks

I honestly was surprised it even remotely worked. Some came out better than other but I'm calling this a success. I sanded some of them down and tried to build a tower.

Step 5: Enjoy Your Concrete Lego Bricks!

Picture of Enjoy Your Concrete Lego Bricks!

Overall, I am very pleased with how these came out. It was mostly an experiment to see if they would even work or not. I really wanted them to interlock like real legos. They sort of did but i think in the future if i spend more time leveling the mix in the mold then it would work better.


KSM6String (author)2017-04-09

You can purchase Lego silicon cupcake molds at any lego store.

stillash (author)KSM6String2017-04-13

I wanted to make my own so i can different sizes and put holes in the back.

WyckedStudios (author)2017-04-09

ROCKITE brand Anchoring Cement is a very good casting medium for craft projects like this. I use it for casting wargaming terrain and dungeon tiles. It has no large aggregates in it, blends to a smooth milkshake-like consistancy, is more durable, and doesn't have those tiny pieces of carbon that make it hard for paint to adhere, like QUIKRETE has.

It does cost a little bit more, but the improvement in casting quality and strength is very much worth it.

stillash (author)WyckedStudios2017-04-13

Cool. I gotta try that.

WyckedStudios (author)2017-04-09

If you dip your molds into soapy dishwater right before pouring in the casting medium, the soap residue will help reduce the surface tension and make it easier to tap/vibrate air bubbles out of the nooks and crannies.

stillash (author)WyckedStudios2017-04-13

thanks for the tip!

SteelLegJ (author)2017-04-04

that's awesome! Lego duplo would probably work great also

stillash (author)SteelLegJ2017-04-13


Koschkien (author)2017-04-04

To avoid the air bubbles, use a vibrating table.

mrsmerwin (author)2017-04-04

What are you planning for the concrete Lego? Are you building something special or just playing?

stillash (author)mrsmerwin2017-04-04

I was just playing with them. I didnt have a set design when I made them.

About This Instructable




Bio: I like making stuff.
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