How to Make "Engraved Stone" Letters in Concrete

As a kid, I always found the names and dates of history dry and boring. Then my parents took me to a museum where we could climb on actual tanks and walk through a simulated WWI trench and I was hooked. I have kids and am married to a teacher and I'm always on the lookout for ideas to add that physical and tactile experience to the classroom. This year, they are studying Rome and Greece and the dawn of western civilization. While I dream of recreating a statue of Cesar or a bust of Socrates, I've set a more modest goal – to recreate a reasonable stand-in for ancient inscriptions...and, as my youngest pointed out, with Halloween right around the corner, this can also be used to make some very convincing Halloween Gravestones.

In this project, we will create the letters "SPQR", a Latin abbreviation for phrase "The Roman Senate and People" that appears on inscriptions in stone monuments and public works. Historically relevant and, more to the point for this Instructable, only four letters long, so much more bite sized.

This project has two main parts -
1) Create the letters for your inscription
2) Make the "inscription" in concrete

Supplies

To create the letters:
Computer with DesignSpark Mechanical software (free) https://www.rs-online.com/designspark/mechanical-... Access to a 3D Printer

To create the final product:
Concrete Mix
Wood for mold form (I used melamine board)
Drill
Screws and other fasteners
Hot Glue Gun
Sander/Jigsaw/Osilating Tool (optional - to work out bubbles)
Cooking Spray ("Pam" works best)
Zipper Style Gallon Sized Freezer Bags
Buckets, measuring cups and/or scoops

Concrete Stain/Pigment (optional)

Step 1: Part 1: Create the Letters

Step 2: 1a) Install Software:

For this project, I used DesignSpark Mechanical
(https://www.rs-online.com/designspark/mechanical-download-and-installation). It's free (they only ask for your email for a free registration), very versatile and there is a large community supporting it with YouTube instructional videos.

Download, install and register the software.

Step 3: 1b) Create New Project:

Open the software and select File>Design to get you a new

Step 4: 1c) Position Grid for Use:

This will pop up a window that looks like this. Select "Plan View" to get you to a front on view.

Step 5: ​ 1d) Create Surface:

Now that you have the grid, select the "Box" tool and draw a box on the plane. Try to keep it more or less centered and it will help out later.

Step 6: ​ 1e) Add Text to Drawing:

Click the "Dimension" tool in the upper right and click on your box. A measurement will show up - try to roughly center this and click.

Step 7: 1f) Edit the Letters:

Select the text and type in your new letters.

Step 8: 1g) Format Letters:

With the letters highlighted, hover over to get a context box. Here change the font size to the maximum (10) and pick which font you want. Ultimately I selected a Sans-Serif font for this project (yes, I had to pass on Times New ROMAN) because the tapering in the serifs limited the amount of tapering I could give the letters. I chose Franklin Gothic Book. It has good spacing, no tapers and comes standard on most computers.

Step 9: ​1h) Make Letters Into an Object:

Now that the letters are roughly we want them, it's time to make them an object. Select the text box of the letters/word(s) and click "Project to Sketch". This will take the text from the Annotation Plane (won't appear on the actual project output) and make an outline in the editable project space. (Special thanks to Q Squared on YouTube. His method using the annotation tool as I show here is _way_ better than all the other methods I've tried.)

Step 10: 1i) Clean Up Non-Essential Stuff:

The letters have been transferred to the box. It's time to clean up the work area. In the upper left, right click and Delete the Annotation Plane.

Next, select, right click and delete the original box you made.

Step 11: 1j) Select Letters for Editing:

Using the Select tool, select all your letters as a group.

Step 12: 1k) Clean Up the Middles:

Switch to the Pull tool and select (holding Control key while clicking allows multiple selections) the insides of letters and press Delete.

Step 13: 1l) Scale Letters:

Select all the letters again and with the Pull tool, pick "Scale Body" from the left. It will ask you for an anchor point to pull from. I chose the lower tip of the "R". This will cause a yellow diagonal arrow to appear. Pull that up and to the left to make your letters bigger. You can key in the final multiple you'd like. I chose , which yielded me a final letter size of about 40mm.

Step 14: 1m) Create Thinner "Offset" Letters:

To make these look more like chiseled, these letters need to be a LOT skinnier, so they can expand out from. To do this, we use the "trace Curve" tool. Found on the top, it creates a scalable outline of an object. Select one letter at a time and apply the trace. I chose an offset of 1.9mm because that made the outlines very tight but avoided overlapping, which would cause issues later.

Step 15: 1n) Remove Original Letter Outlines:

Now that we have the skinny letters we need, delete the original text outlines. In DesignSpark, if you click on a line once, you'll select that line. Twice will expand the selection to adjacent pieces. Three times will select the whole object.

Triple click each of the outlines and delete the original letters, leaving only the skinny ones.

Step 16: 1o) Clean Up the Middles:

Again use the Pull tool to select the insides of the letters and delete them.

Step 17: 1p) Spinning the Letters:

Since we're creating letters in concrete by making an inverse (it makes a letter by keeping concrete out of the space), to do that we want it to, we need to work from the back side of the letters.

Select the Spin tool and spin the whole group so we're facing the back.

Step 18: 1q) Pull Letters Into 3D:

With all of the letters selected, click and move the Pull tool to make the letters 5mm high (start to pull, then type in the value of 5)

Step 19: ​1r) Taper the Letters:

One at a time, with the Pull tool, select one of the letters, then from the left, pick the "Draft" tool. This will allow you to create tapering around the entire object, starting at a face (that's why we spun it to the back) at the angle of your choosing (provided it does not interfere with any other curves on the object). For this project, I chose an angle of 10 degrees, since that looked most like the monument pictures I was using for reference.

Step 20: 1s) Repeat for All Letters

Step 21: 1t) Save As (Export) an STL File:

In DSM, you have a lot of output options. Pick one that is compatible with your slicer/3d printer.

Step 22: 1u) Import Design Into Your Slicer Software

Note- The design will be positioned upside down from how you want it to print. Be sure to flip the design so that it prints wide side down.

Step 23: 1v) Print the Letters

Step 24: Part 2: Make the "inscription" in Concrete

Step 25: 2a) Gather Your Box and Mixing Materials

Step 26: 2b) Screw Together the Box

If using melamine, make sure the shiny side is facing towards the middle.

Step 27: 2c) Seal the Seams

On the outside, use tape. On the inside, seal them with hot glue.

Step 28: 2d) Position the Letters in the Box

Getting the letters straight can be tricky. This is what I did - I had printed the letters with a raft. This gave me an opportunity to use the positioning of the letters on the raft to keep them in alignment. To take advantage of this, I drilled holes into the raft and marked alignment dots onto the surface. This allowed me to keep the letters straight when I glued them.

I drew a line with a straight edge inside the box to mark the top.

Step 29: 2e) Sand, Prep and Glue the Letters

The letter will need to pull out of the mold, so get them smooth! Sand the letters then glue them to the base.

Step 30: 2e) Mix Up and Pour the Concrete

For very small batches of concrete, I prefer to mix it in a gallon ziplock style bag. That way, I can really see that the water gets fully mixed. Be sure to mix based on the instructions on the bag. Many bags just have the amount of water to mix a full bag - a) be ready to do some math to find the measurements for smaller batches and b) always start using less water than you think you need. You can always add more but can't take away if you add too much. You can stiffen it up my adding more dry mix if needed, but also have a place to dispose of excess concrete if you mix too much.

Before I put the concrete in the mold, I give the mold a shot with non-stick canola spray (I use "PAM" brand). This will act as a mold release. When the concrete is poured, it is important to get the bubbles out. This can be done by smacking the side of the container and additionally by applying some sort of oscillating power tool around the outside of the box. I didn't have my sander with me, so I subbed in my jigsaw with the blade removed.

Step 31: 2f) Allow to Dry and Unbox

When the drying time has passed, carefully remove the sides and pop loose your creation.

Step 32: 2g) the Moment of Truth...

Ultimately, the process when very well, though the full final project has some issues, most stemming from my impatience and not letting it cure fully. Also the letter "P" got concrete under it and had to be dug out.

As you can tell, the letter "S" turned out well. It could have used a longer in the drying phase and in my haste to un-mold it, I also cracked it..

Step 33: 2h) Final Notes

Here are some things I learned from the project:

1) Make sure to let your mold dry sufficiently. Better to wait too long than risk damaging your final product.

2) Printing the letters attached to a flat plate under the letters will help solve both the spacing and adhesion.

3) If mixing concrete in a zipper bag, remember to use the Freezer variety. The gravel in the mix easily punctures the standard bags.

4) Always have extra materials on hand. Sealing seams eats through glue sticks very quickly.

I have included my STL file with this project in both the original and with backer plate versions.

Enjoy!