3rd Birthday Construction Cake (For A DIY Construction Birthday Party)

I know so many little boys (and some little girls too) who are obsessed with construction trucks! Lucky for us moms, it’s actually really easy to make a great DIY 3rd Birthday Construction Cake at home. You can swap out the number carved into this cake with any number to make it perfect for whatever age your little one is turning. A construction themed birthday cake takes a bit of planning and you’ll need to gather a few materials, but trust me it will pay off and look great and it’s actually super easy to decorate!

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This isn’t geared towards professional cake designers, I know I’m an amateur cake decorator at best. HOWEVER, it doesn’t matter if the icing is perfect. A construction birthday cake is very forgiving because sometimes things get muddy at the dig site. Your child is just going to be thrilled you made them such a cool dig site cake for their construction themed birthday. It tastes great too!

  • Ingredients:
  • Eggs
  • Oil
  • Water
  • Box chocolate cake mix
  • Reese’s pieces
  • Kitkat bar
  • Oreo crumbs
  • Black sprinkles
  • Whoppers
  • Can of chocolate icing

Preparation and Baking

To get started making this cake, follow the instructions on your box of chocolate cake mix the night before you need it. Baking your cake the night before your big event can save you stress the day of and give the cake enough time to cool off before you decorate it. My cake mix called for eggs, oil, and water before I mixed it all up with my mixer in a bowl, and baked it in a glass pan for 30 minutes. 

Once my cake was finished baking I let the whole thing cool off on my counter, put saran wrap on it, then stuck it in the fridge overnight. It can also be helpful to put your cake in the freezer so it’s easier to put frosting on it.

There are a few more things you can do the night before so you’re ready to decorate the next day. Make your yellow and black striped cake board, crush your cookie crumbs, wash your toy construction trucks, and cut out your number 3 you’ll use as a stencil. 

To make my cake board I used yellow poster board and black electrical tape. It really gives the cake an extra special construction zone birthday look. I scraped off the oreo whites, put the chocolate parts in a ziploc freezer bag and crushed them until they were very crumbled. You could instead crush them in a food processor if you have one.

The night before I also used wax paper, cut it the size of my glass pan, and wrote a big number 3 on it with a marker. I’m not going to lie, it took several attempts before I got the 3 to look right. 

It can be very helpful to use the number 3 sheet of wax paper to plan out your cake before you actually start decorating. It will give you a good idea of what things will look like before you place them on your cake, where you might not be able to ‘un do’ any decisions you’ve made. Sometimes less is more… I bought a whole package of miniature construction trucks but only used three of them for this cake so I didn’t overwhelm how it looks. I also bought a ton of chocolate candy and placed it sparingly but we’ll get to that later.

Construction Cake Decorating

Once your cake is cold, it’s time to decorate… this is the fun part. Place your number 3 stencil on top of your chocolate cake and then score it with a sharp knife. Go slow and be careful – you only get one stab at this (ha ha). Use a spoon to scoop out the top of your number 3; you don’t have to dig too deep into your cake. Put your crumbled cake pieces in a separate bowl for later (the parts you scraped out to make the number). You could use them as part of your construction cake decorating later as edible dirt but I chose not to. You could also save it to make cake pops with.

Use your icing bag and tip to frost your construction sheet cake with a border that your Reese’s Pieces will be able to stick to. Fill in the rest of the top of your cake with chocolate icing, but don’t put any icing inside your number three.

Carefully spoon and sprinkle the crumbled oreos into your number three dig site. I liked adding in a few black sprinkles to the oreos to give the cake a bit more sparkle. 

Alternate colors of brown, orange and yellow Reese’s Pieces to create a pretty border around your third birthday construction cake. Place your Kitkats to look like logs and your Whoppers to look like boulders around your construction site cake. 

Then add in your miniature toy construction trucks. I used a touch of chocolate icing to keep the Whoppers from rolling out of the back of my mini toy dump truck. 

Place your finished cake in the fridge until you’re ready to serve it. At party time, you can set it on top of your yellow and black hazard sign cake board and spread out a few of your construction trucks around the cake to help tie in your birthday theme more.

Voila! You have your very own 3rd birthday construction cake that your kid and guests are going to love. Your child’s 3rd birthday is going to be so memorable and I’m sure this cake is going to be one of their favorite parts of the whole day!

Extra Notes

Construction cake topper toys: I purchased a set of construction vehicles to use as cake toppers for this themed party. If you’re putting used construction toys on top of the cake, or even brand new ones you’ll definitely want to wash them first. Here is a link to the exact construction vehicle set I used to make the cake seen in these photos. To be honest, I’m not super impressed with the quality of these toys, and they have spelling errors on them. BUT they’re the perfect size to put little diggers on top of a construction party cake without sinking too deep into your chocolate buttercream.

There are some other options you can find on Amazon and Party City that sometimes come with mini toy construction pylons or cones. Feel free to get creative with your toy trucks. These are really fun cakes that your party guests are going to love and they’re also pretty simple cakes to make. Instead of using a poster board and electrical tape under your cake, you could use caution tape around it.

If you don’t have an icing bag you can put your frosting in a large ziploc bag and cut a hole in the tip of it. If you’re going to use a rubber spatula to spread icing on this cake, be extra careful around the number dug into the cake so it doesn’t crumble. In fact, you may want to freeze your cake to make it extra firm before you ice it with a spatula. 

I hope this article helps you make an awesome DIY 3rd birthday construction cake for your construction themed birthday party! It’s such a fun theme and it’s a really forgiving and easy cake for a complete beginner to try and put together.

For more fun party ideas, check out more of our articles here on Mama’s Buzz!

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