The Letters

When our first son was born we decorated his room with the letters of his name by ordering a set of modern, wall-mounted letters online. When we were expecting our second son, we also planned to put his name up on the wall, but instead of buying the letters, we decided to make them ourselves.

My initial idea was to use a laser to cut the letters out of layers of wood and acrylic. The wood would be against the wall, painted white, with keyholes hidden and cut out of them so they could be hung on the wall. A thin piece of translucent acrylic would be adhered in front of 2 or 3 layers of ¼ inch sheets of wood. The acrylic would give the front surface a glassy look just like the old white iMacs, or EVE from WALL-E.

I really wanted the edge of the acrylic to be cut flush to the edge of the wood, but I realized the challenge would be to get the acrylic to stick to the painted wood. I don’t have much experience using acrylic and my guess is that even with something like acrylic cement, getting it to stick to the paint in a clean and attractive way might be an issue.

I discussed this idea with my friend, Ian from Roc City Laser, and we came to the idea of using epoxy as an alternative to acrylic. I hadn’t cast epoxy before so I really liked the idea of testing it out for this and future projects.

Part I: Material Test

Easy Casting

My first step was to get some experience mixing and working with a two-part epoxy. Because epoxy is very expensive I picked up a small kit of EasyCast for my first test.

The two-part kits usually contain the epoxy in one bottle and a hardener in the other. When the two combine, the chemical reaction hardens them and cures into a solid piece.

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I remember hearing a tip about reducing wasted epoxy by measuring out the volume of your mould using water and marking your mixing container for both parts. I was planning on using a silicone mould of some LEGO-like figures, so I started by filling it in with water, then I poured that water into a measuring cup. It came to about 3.5 oz., so I rounded up and measured out 2 oz. of water and poured it into a mixing cup, marked the cup with permanent marker, measured out another 2 oz., added that to the cup, then marked the cup at the new level.

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I followed the mixing instructions to fully combine the epoxy and poured it into the mould.

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Because I’ve seen makers embed things in epoxy, I grabbed a couple of actual LEGO pieces and used a bamboo skewer to lower them into the mould. What I found was that the pieces did not float or stay suspended, but they did stay put once they sank to the bottom of the mould. I’d still like to figure out if there’s a way to hold the items in place, but this wasn’t an important part of this particular test.

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I picked up a heat gun and used it to pull up as many bubbles as I could. It was difficult to get the bubbles from the bottom of the mould, but I wonder if it would help to only pour a thin layer, use heat to pull out the bubbles, fill in the rest of the mould, then remove the remaining bubbles.

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I had to take a moment to appreciate the glow of the UI on the heat gun. This looked just like a light-up effect from a movie.

The epoxy took about 24 hours to harden enough where we could pop them out of the mould. I popped out the first one, then had my assistant pick out the rest.

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The figures standing on top of a performance of Radio, Radio by Elvis Costello and the Beastie Boys.

My first impression is that these looked great. I can see where I had poured too much or too little and how the meniscus from each affected the backs of the figures. The EasyCast did not seem to completely harden, but instead it’s almost like a very hard rubber. The bubbles in some of the corners were noticeable on the larger figure, but not as much on the smaller figures.

Mould Test

At this point I was convinced that the epoxy would work, so the plan was this:

  1. Use the laser to cut three layers of letters out of the wood
  2. Glue up and paint the three inner pieces for each letter
  3. Glue up and seal the outer pieces to create moulds to pour the epoxy into
  4. When the epoxy would dry, slide the epoxy out and wet sand it to a perfect, shiny finish
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Ian used his Glowforge to cut out the letters from ¼ inch plywood. We created two variations of the letter W”, and one rectangle that might represent the thickness of one of the letters.

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I glued up the letters into stacks of three, and glued the moulds into stacks of two. After a quick sanding I painted the letters with spray paint and let them dry.

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I used silicone to seal everything up. At this point it might have been a good idea to test the moulds by pouring water through, but at the time I didn’t think about doing that.

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I ordered a big kit of two-part marine epoxy and hardener. I figured I would use it all for this project or if I had extra I could use it for future projects.

I also ordered a blue, glow-in-the-dark pigment for fun. I wasn’t planning on using it for the letters project, but since I’d be testing out the new epoxy I thought I would play around for some other projects I have in mind.

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I mixed the epoxy to test my moulds, but I also wanted to do a test for sanding the epoxy, so I poured another round of the LEGO-like figures.

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I planned to wait about 24 hours for the epoxy to harden, but they were dry enough to take out around 18 hours later.

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I took out the figures and had some fun testing out the glow-in-the-dark look. The pigment worked really well!

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The larger figure looked awesome and after a good charge in the sunlight or with an LED, it can glow for hours.

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Unfortunately the moulds were another story.

A lot of epoxy leaked out of the letter moulds and they became very messy. Also, I wasn’t confident I would be able to wet sand the epoxy without messing up the layers of paint.

My plan relied on the pour to go smoothly as it would be very hard to repair issues with the paint after the fact. I could have kept working towards a solution, but we were getting close to our due date so I decided this wouldn’t be the way we would do the final build.

This still might not be a terrible idea, but if I were to try it again I would look into making my own rubber mould from the laser-cut letters, pouring the epoxy down into the mould, then finding a way to place the letters on top of the epoxy in the moulds.

Part II: Pivot

With time running out, I decided to go much simpler for the final solution.

Design

The idea of using the Glowforge to cut layers of plywood into the letters was still the plan, but I wanted the do something unique for the top surface. Ian had suggested doing epoxy inlays and I really liked that idea, but it still had its own set of challenges that would need to be tested out.

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I was looking through some of my old photos for ideas and came across the surface of an object that had a halftone pattern cut into it. It’s super simple, but I really like the textured look and since we were planning on using the Glowforge for the cuts, adding an engrave step to the top layers would be super easy to do.

I designed the files and sent them along to Ian with one cut layer and one engrave layer.

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Production

I picked up a large, 4x8 sheet of ¼ inch plywood and got it to Ian. He brought me back a couple of test letters so we can see how deep the engrave should be and to see if the size worked. They looked fantastic.

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With a few minor adjustments, the plan was moving forward and Ian put together a quick test piece to see how everything would come together. I used this to test out the spray paint to make sure the engraved pieces would fill in correctly.

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Ian cut out and engraved all of the letters and dropped them off. The engrave looked great and the letters all stacked nicely.

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Between Ian’s suggestion and hearing a tip about buying wood glue in bulk, I bought a GlüBot and a gallon of wood glue. Ian also recommended silicon brushes to apply the glue. The cool thing about these is that you can just let the glue dry and peel it off very easily.

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I did a quick dry run to make sure all of the letters lined up and that I had them all right side up.

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My original plan for the keyholes was to use a keyhole router bit to cut into the back of each of the letters, but Ian had the idea to use the laser to cut the keyholes into the bottom two layers. This design worked perfectly when it came time to hang the letters.

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Most of the letters were made up of flat edges and corners so lining them up was very easy. The O” on the other ̦ was a little harder to line up and this would have been an issue when getting to the glue up step.

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When cutting out the O” the laser left a small mark on the inside piece in the same spot for each layer. This was super helpful lining up the layers in the dry run.

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I used a technique I see in a lot of tabletop glue up where I took a pencil and made a squiggly line on the outer edges. Between the squiggly line and the marks on the inner cut I was able to put the letter back together quickly when it came time to gluing the layers together.

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After gluing all of the layers of the letters together and waiting for them to dry, I sanded down all of the edges. While the Glowforge cut the edges very flat and accurately, I wanted to remove a little bit of the burn mark to make it easier to apply white paint later on.

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You can see the burn mark coming off when sanding with 150 grit paper

I applied a thin layer of wood filler around all of the edges. This filled in a couple of gaps that the plywood had, but it also flattened out the very small gaps between each layers.

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After sanding down the wood filler, I painted the letters with spray paint and let them dry over night.

Hang Time

I wanted to make sure the spacing and alignment of the letters were correct before putting them up onto the wall, so I found a large piece of paper and laid the letters out on top of it.

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I started by drawing both the ascender line and baseline guides onto the paper.

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My wife, who is the resident designer, kerned the letters and helped me line up the keyholes on the backs of each letter. We did this by tracing the letters, holding the paper up, and popping a hole into the top of each keyhole.

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With the keyhole markers in place, I leveled and taped the paper onto the wall. I marked the wall and used a screwdriver to create some pilot holes. With screws in the wall, the letters were ready to hang.

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Fin

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Even though the original plan for this piece turned out to be very different from where I started, I’m happy with the final outcome.

Working with the epoxy really sparked some ideas. With all of the extra epoxy I now have, I’ll probably get started on them sooner than later.

The Glowforge really helped make this happen in that it allowed me to experiment and come up with several options and quickly see how they would work before spending hours committing to one solution.

I just hope my son enjoys these letters as much as I enjoyed making them for him.