Introduction: 3D PRINTED CONCRETE MOLD

Picture of 3D PRINTED CONCRETE MOLD

This is something I made for my mentor, Denise. I got the inspiration from browsing concrete planters on Etsy, however, I was stunned at the asking price (range of $30-$70) for these things. So I did what I naturally do after discovering something that piques my creativity. I asked the burning question, can this be recreated using technologies such as 3D printing and for much less AND share it with others? Yes indeed, it can be recreated using 3D printers. The awesome thing about these 3D printed molds is that they LAST a long time and continuously produce quality and consistent planters.

I did some research. I found out that you can make these for less than one dollar each (17 cents). I have provided the final mold file (STL) that produced the best results. This mold is meant to be 3D printed (PLA, or ABS, does not matter). Infill does not affect the mold too much, but of course, the higher the infill the more planters you are going to produce out of a single mold. I used 20% infill, 3 shells. Combined, my molds have produced almost 100 PLANTERS!!!

Step 1: Baby Step 1

Picture of Baby Step 1

First, I started with an idea. I wanted to create something aesthetically pleasing so I can gift to friends and family. I set out and gave myself criteria to follow.

1. It has to look modern

2. Functional: it can be used as pen holders, etc.

3. Easy to make: easy as mixing cake batter (water + mortar + spatula + oil pan or another container to mix contents)

4. Cheap, cheap, and cheap: an 80 lb concrete (mortar) costs no more than five bucks and yields about 30 planters (that is 17 cents per planter!)

Step 2: Gather Tools and Materials + Procedures

Picture of Gather Tools and Materials + Procedures

Tools

1. Container to mix mortar

2. Trowel or mixing stick: mix concrete

3. Dowel or other flat-edge to screed excess mortar

4. Air purifying mask: at least an N95 as silica exposure can damage lung tissue)

5. Disposable gloves: to apply vegetable shorting (release agent) on the inside of the mold

6. Rubber mallet: Any will do. I bought mine at the dollar store

Materials

1. Mortar: I bought an 80 lb bag at my local home improvement store for less than $6.

TIP: A lot of people confuse mortar with concrete. Although they look similar, they are NOT. You want to use mortar because mortar is sand mixed with cement whereas concrete is a combination of both sand and cement AND rocks. You do NOT want rocks in your mold as they will cause problems.

2. Potable water: if you can drink it is good for mortar

3. Vegetable shorting: this is our release agent. It is the cheapest thing that works like any other petroleum/jelly release agents on the MARKET

4. Dyes or colorings (OPTIONAL): I find that if you do not use dyes or colorings + sealer, the finish is somewhat bland (ashy gray)

5. Aerosol sealer (OPTIONAL): again, this is optional but it will give your product a nice finish that will last forever

Procedure

1. So basically, just download both STL files (mold A is the shell and mold B is the cavity part) and 3D print with a 3d printer. It should take about 6 hours to print both halves on a conventional FDM (fused deposition modeling) printer. I used a RepRap Prusa i3.

2. just follow the instructions on the packaging the mortar came in OR, you can use this rule of thumb that always works: 1 part water for every 5 parts of mortar. Print as many molds as you want and calculate the amount of water + mortar

2. Mix: at this point add any dyes if you have any

3. Apply "release agent" on mold

4. Fill mold with mortar, slightly overfilling it, and screed with a dowel or other flat-edge device

5. Wait 24 hours to cast mold; cast mold by hitting mold B (cavity) with a rubber mallet. This will cause the two halves of the mold to separate

6. At this point, apply any coloring to the planter. If you have colorings, follow manufactures recommended instructions

7. Apply a few passes of sealer (you can use the sealers that come in a can but I find that those are troublesome and messy since they require a brush of somesorts)

Comments

greenbriel made it! (author)2017-11-02

Great project, thanks for sharing. Been wanting to 3D print molds for a while and this got me off to a great start. Looking into multi-part molds next.

I printed in nylon as I figured the mold might take a bit of a beating when getting the cast out (it did). Worked well but left a crazy residue on my print bed - I thought it was warped for a while but I was able to scrape it off with paint scraper and razor blades. Weird.

I finished with a couple of coats of Tuff Duck. I plan on designing original molds and offering planters for sale, but as I already have this mold printed I wondered if you'd mind if I offered casts of this design too. No worries if not! Thanks!

PS I know my plant is too small, hoping it'll grow! :D

EshRobotics (author)greenbriel2017-11-09

Were you able to remove final part and keep the mold for future casting?

Porda (author)2017-10-31

Awesome planter! I'm trying to do a 3D printed concrete mold and I was wondering what material you used for printing. Was it PLA?

greenbriel (author)Porda2017-11-02

He said "This mold is meant to be 3D printed (PLA, or ABS, does not matter)"

Of those two I'd probably go with ABS for strength, the mold takes a bit of beating when getting the cast out (even with a coat of Pam). I used nylon which may have been overkill and stuck like hell to the print bed. PETG could be best of both worlds (strong and easier to print).

Porda (author)greenbriel2017-11-03

Thanks. Don't know how I missed that. In too much of a hurry I guess.

greenbriel (author)Porda2017-11-04

Haha, no worries :) I'm wondering if there's a perfect semi-flex filament that could be rigid enough to support the concrete, but might make demanding easier.

Give it a go, it's a great project!

Swansong (author)2017-06-15

That's a pretty planter :)

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