Introduction: Soundboard Cake With Working Volt Meters

About: Artist at Autodesk's Pier 9. I make narrative paintings on wood panels and have a background in performance, mail and video art. I love tacos.

I tell you what. My patronus is a cake, that's what.

This Instructable will cover cake decorating methods and contains tips that will help all other manner of cake decorating.

Anything can be a cake.

This cake is great for music production geniuses named Scott turning 40. With a few changes it can be tweaked for music production geniuses named Scott who are turning 41 or even music production engineers named Kevin who are turning 28.

The sky is your limit.

I'd like to thank MVP and best all around winner, Joe Joe, for hooking me up with with the electronics for the volt meters.

Step 1: Plan Your Attack & Gather Supplies

I drew out the cake I wanted first, so I knew what I would need to make and could be efficient with my time. It's a labor intensive cake.


  • 3 yellow cakes (any recipe or box)
  • 1 box of white fondant, 1 black
  • Powdered sugar for dusting
  • Vegetable shortening for smoothing
  • Powdered egg whites (For "gluing" fondant, you can use an alternative)
  • Chocolate ganache (Step 3)
  • White buttercream (Step 4)

Special Tools

  • Self contained LEDs ( I used waterproof ones since they were going on a cake)
  • Working Volt Meter with battery (Instructable to come!)
  • Tape
  • Offset spatula (Not mandatory but very helpful)
  • Wood or particle board (People usually use cardboard as a base layer for these types of cakes, but this one is super heavy and needs an adequate platform)

  • Rolling pin with rubber band guides (to get an even thickness of rolled fondant) is very helpful but also not mandatory a regular one works fine

  • Small Paint Brush reserved for edibles

  • Fondant shaping tool kit (I have the Wilton one)

Step 2: Prepare Cakes

1. Find cake recipes:

  • If you are looking for a cake recipe, pick one with a dense crumb so it can hold up to heavy decor. You are looking for standard issue pound cakes. Any flavor is fine. Try to stay away from light, delicate cakes like Chiffon, as they don't hold up to the abuse of decor well.
  • You can make box cake too! Don't let not wanting to bake keep you from decorating!

2. Bake cakes according to recipe. You'll need:

  • 2 rectangular sheet cakes (usually 9 x 13 in pans are common)
  • 1 loaf pan sized cake

3. Cool cakes overnight. This is really important. So often cakes mess up because they get decorated early. Cakes need to chill completely and mellow out so the icing doesn't slump off.

4. Trim cakes with knife. Cut the top crusts off the cakes so you get a flat even surface and it creates a good surface for icing to adhere too. I trimmed the loaf pan cake diagonally to make the console top and patched up flaws with cake crumbles.

Step 3: Chocolate Ganache


  • 4 cups of chocolate chips (dark was used here but go with your flavor)
  • 2 cups of heavy whipping cream
  • 1 stick of butter

Combine chocolate and cream in a double boiler. Melt the chocolate gently into the cream with intermittent stirring. Remove from, heat and whip a stick of room temperature, soft butter into the chocolate cream. Whip it. Whip it good.

Let it cool. It can sit around in the fridge for a few days, if you want to make it ahead. If it gets too hard to spread easily, let it sit out a little bit just whip it again. If it is too thin even chilled, and you are out of chocolate, add a little powdered sugar to stiffen it.

Step 4: Buttercream Icing

  • 2 Sticks of soft room temperature butter
  • 1 lb of powdered sugar (sift if lumpy)
  • 2 teaspoons of vanilla extract
  • 1 tablespoon of meringue powder (optional, but helps hold shape longer or in warm weather)

Whip the butter first till it lightens in color and is fluffy (Under 1 minute on a kitchen aid.) Add the extract and gradually whip in the powdered sugar .

Hot tip: powdered sugar is messy. Put saran wrap over and around your stand mixer. If you're using a hand mixer, you'll have to go reeeeeealy slow.

Prepare your wood board or heavy duty cake tray that will support your cake by lining the edges with parchment paper. These will slide off cleanly when you are done so you don't have buttery ganache marks on your board. Put a dab of buttercream on the board. This will act like glue to secure the first layer of cake cake.

Step 5: Frost the Cake

Layer your cakes with an even spread of about a cup of ganache. This is why we made so much ganache. It's much trickier to be stingy with it. An offset spatula rules for this job. It's hard to be even without it but even a butter knife will do with patience.

You'll want to use more than half of the total ganache to cover the surface. After the final layer is on, refrigerate it the cake for about half an hour. Flatten out the chocolate again with a clean spatula. Pay attention to the edges. Try to make it crisp and clean, not rounded.

Step 6: Make Knobs, Levels and Simple Components

This takes a long time, but it is exactly like playing with fancy play dough.

  • Look at photos of your sound board. Figure out what you need to include and what you can cut out.
  • Knead the fondant in small batches. I used some homemade fondant I had from a previous cake and supplemented with store bought fondant. It is great to buy black fondant for this because coloring anything that dark is very hard and affects the texture terribly making it a mess to work with.
  • To dye your fondant, always use gel colors and not liquid, you can add color in in small increments using toothpicks. I greyed out most of my colors using black.
  • You don't need to have a sculpting set. You can easily use random things in your kitchen to shape the fondant or just your fingers.
  • To make round buttons, I rolled the fondant in small bits in my hands and flattened them out with my thumbs.
  • Tapered knobs like volume knobs can be made by rolling out a piece of fondant with your finger tips, applying pressure more on one side.
  • I made flat indicators by rolling the fondant and cutting it up with a knife to get the shape I needed.
  • Letters were made by shaping "snakes" of fondant first then rolling them out flat.

Step 7: Ready Your Volt Meter

The volt meters were wired and arduinoed up by Joe Joe and are attached to 9 v battery. I wrapped these in plastic and tape and fondant to ensure relative food safety. Little did I know at this stage to always use a fresh battery. It turns out that at critical times, far removed from your supplies and resources, you will have to solder and rewire everything in hopes of getting something to work. You will do this over and over and over and over again, only to find out that the battery has been dead to whole time. I don't work with electronics so this was a new revelation to me. I have learned! Don't be me. Take spares and repair kits. I usually take a cake repair kit with me for elaborate cakes but did not even think of the electronic bits.

(A cake repair kit for this cake would be a ready to go baggy of icing with tip and a fist full of dark grey fondant)

Step 8: Levels and Other Meters

AHA! Flat bits are a breeze. Try to keep your fondant an even level. A dusting of powdered sugar is helpful with fighting stickiness. If your fondant is too dry, you can work in a bit of shortening. Which is a also a good trick for smoothing out cracks.

To attach fondant to itself you can use brush on an egg wash or even just water. I use water with a pinch of meringue powder to get a little bit of tackiness.

You can make the decorations far in advance. Weeks! Fondant don't care. It's not there to be delicious. You, at least, should give these guys 24 hours to dry out.

Step 9: Cover Cake in Fondant

I'm not the best at this part but I've gotten ok at hiding flaws.

  • Mix a pound of black fondant with about a third white to make a dark grey that will be the main plastic surface of the soundboard.
  • Roll it out to about 1/8 of an inch on two sheets of parchment paper with a liberal dusting of powdered sugar.
  • Check you sizing using the cake pan.
  • Remove the protective parchment paper from your cake.
  • Using both hands, support the giant fondant disc and the parchment paper from the center and place it on cake.
  • Adjust it some more and then remove the parchment paper. The affect is similar to yanking a tablecloth from underneath a set dinner table. Voila!
  • There are special fondant paddles to smooth it on the surface. You use both at the same time to support the cake with one and sweeping with the other across the top and sides of the cakes. You can also smooth using your bare hands like a bear or another animal that has no fondant paddle.
  • Cut the extra off but leave an overhang of about 1/4 in. that you can tuck in under the cake. This is super great as if it's warm or the cake sits out it creates a sturdy sealed protective the delicious cake parts in an armadillo's armor of sugar paste.
  • If it still looks a bit dodgy or lumpy, you can, as I did and often always do, make a decorative border and hide your mistakes.
  • See that Crisco? I rubbed it in the fondant to smooth out bits and and make the fondant look more glossy and plastic like.
  • Saran wrap is purely protective at this stage of the fondant from spills.

Step 10: Decorate

My quick trick for icing is to get a gallon ziplock bag and snip a corner off. I find that bags are way easier to use than the triangular icing bags they sell which are too thick and overpriced.

Drop the metal icing tip in and you have a perfect bag. The easy way to fill a bag up is to place the bag nozzle down in a cup and unfold the edges over the cup. Fill it with a spatula or spoon. Always under fill, try to keep it under half full. Practice piping some lines first and feel it out for air bubbles. If your icing is too soft, throw it in the fridge for a couple of minutes. I pop the bag in the fridge several times while icing a cake because my hands warm the bag up and it messes up my lines.

Icing attaches all the bits and knobs and thingies to the cake and you can draw with it and outline your cake to give it a comic book feel.

Icing is best. It is sugar butter.

Hot tip: Resist all urges to taste icing. I feel, and I have no evidence for this, but working with sugar absorbs in through your hands or something, because even the smallest taste of your sugar bomb creation will give you that "I had too much sugar and now feel sick" feeling. Be zen and don't eat the cake while you're making it. It's too much! Maybe this goes without saying to other people.

Step 11: Electronics

Cut a square out of your cake just big enough for your volte meters to fit. I used an ice cream scoop to get the cake out.

Line the cavity with saran wrap and insert the volt meter. I used some extra fondant scraps. to seal the edges. You should make this an easy to reassemble and remove bit as you will probably not plug the battery in until later and you don't want to feel sad if you need to make adjustments like oh I don't know... replace the battery.

Step 12: Ta Dah!

The LEDS I got advertised themselves as being water proof, so I figured that would work for a cake. It worked great on that end but waterproof means bulky and I was a bit disappointed at how large they were and didn't want to plug them in everywhere into the cake and make a mess. I made little fondant circles to support the LEDs so they could be placed on or near the fondant without inserting them in fully into the cake.

And here's my very last hot tip! No one likes to eat fondant but it is great for decor and for keeping a cake fresh. Do what I do and don't serve it! I cut the cake up and peel off the fondant before serving each slice. Sometimes, I have insane sugar crazed friends around and they eat all the fondant. That's pretty gross. Don't do that.