Erupting Volcano Birthday Cake




About: I have had a few careers so far, soldier, school teacher, arborist, millwright. I love change and I love learning.
For my son's 5th birthday, I decided to go a little nuts. 4 months and about $200.00 later I think I created something one of a kind.
I wanted a volcano that would do several things...


erupt with lava


and finally, make volcano noises.

Please check out my other instructables and I also have a diy podcast called


Step 1: Lava

I was thinking of making my own piston type lava delivery system, but then I realized I had a perfectly good one sitting around the house already. We have a chocolate fountain we bought for $75 a year ago. Everything for the cake was built around this.

The actual lava was made by blending a $10.00 bulk bag of frozen strawberries with some icing sugar and corn starch. This was reduced on the stove to thicken. The flow rate was tested and the sauce was frozen. This was a mistake because I think freezing the sauce changed it's consistency slightly and it did not flow as well as I would have liked on the big day.

Step 2: Making the Pan

The pan was made from an old stainless counter top. I cut and welded the pan with an angle grinder and a tig welder. The hole was cut with a drill and a hole saw. I ended up building a tower on top to extend the volcano higher and to reduce the volume of cake required.

Step 3: The Box

The box to hold everything was made from 5/8" thick MDF
I used a flapper disk on my grinder to round the edges and it worked really well.
I painted the box with a textured spray paint that looks like rock.
I welded the handles up and mounted them a little off centre to compensate for the weight of the fountain inside.

Step 4: Making It Vibrate

I took a motor for a power wheels jeep, welded a clamp and offset counterweight. It had to be clamped very securely to the box to transfer all of the vibrations. The motor was powered by a 12v power supply. The power supply for this and all other electric devices were switched on by a remote control that is used for Christmas tree lights.

This worked awesome and actually shook the whole table the cake was sitting on.

Step 5: Making Smoke

Smoke may be a bit misleading but this was actually the most spectacular part of the show. Watch the video at the start to see.

It was made from a teaspoon of coco powder in 2 "shooters" powered by balloons. Each balloon sat in a holder hidden inside the box. A pin held the balloon in place. A slow turning motor pulled a string attached to the pin. (the motor turned too slow so I added the arms to increase the radius) Once pulled, the air rushes through tubing to the pan. Inside the tower of the pan is a loop in the tube. This holds the coco powder close to the end and allows me to separate the tubes between the pan and the box without the coco spilling out the bottom.

When this went off we somehow got 4 bursts out of 2 shooters. I still don't know how it happened but I guess it is better to get more than you expected than less.

Step 6: Creating the Sounds

To sound like a volcano, I mixed sounds I found on the net. What you hear in the video is a combination of a fireworks show, bubbling soup, and rolling thunder. To play the sounds, I used an I-pod nano hooked up to an old set of computer speakers. The nano played a continuous loop of the sound effects and when the power was turned on via the remote, the speakers turned on and the sounds could be heard clearly even in a crowded bowling alley.

The picture here shows how everything fit into the box.

Step 7: The Cake!

This part took me about 8 hrs, 7 cake mixes, and 11 cans of icing. I have made my own cakes and icings from scratch before but this time I just wanted to get it done quick (if you call 8 hrs quick). You can see to tubes for the coco powder shooters hanging below. They are visible sticking out the top of the volcano if you look close. I also dusted the top of the volcano with icing sugar to make it look kind of snowy (not shown in this picture) I placed enough plastic dinosaurs (bought in packs of 6 from the dollar store) around the volcano that every child at the party would get one with their slice. I made sure to place a few of the dinosaurs in the path the lava would take.

What a project!



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    74 Discussions

    dave spencer

    12 years ago on Introduction

    OK, I'm not sure if anyone is going to be interested or not but here goes...

    This cake box/ pan thing is too big for me to want to store. I will never use it again and it is too small to get any reasonable materials from scrapping it so I am giving it away. That's right you read correctly, I'm giving it away.

    For the low low price of $0.00 you get:
    a stainless steel pan,
    a rock textured wooden box with handles,
    a vibrating motor,
    Electrical plug with splitter box,
    the motor that pulls the balloon releases,
    I'll even throw in a few extra balloons and some of the plastic tubing.
    MP3 file for sound effects
    Free tech support

    I will NOT be giving away:
    My wifes Ipod Nano and speakers (sorry, I asked)
    The chocolate fountain (I know its an important part but we got ours new for $75 and we actually use it as a chocolate fountain)
    Power supplies (one 12v and one 6 v for the motors)
    120v remote control
    cake mix or icing

    If you live in the greater Toronto area and don't mind coming to pick it up (it's too big to ship reasonably) it could be yours. All I ask is that you make another child happy and try to pass it on again after (maybe with a few more of the required parts) It would also be cool to see pictures.

    First email gets it. I do offer a 100% money back guarantee!

    7 replies

    Congratulations to Mike! He just picked up the cake. He says he is going to use the volcano with bread and chili in a chili contest. VERY COOL. Best of luck Mike and I can't wait to see pictures!

    canidadave spencer

    Reply 11 years ago on Introduction

    That's fantastic! Pictures, sure- the chili modification process should probably get its own Instructable. I can't wait!

    colorslamdave spencer

    Reply 12 years ago on Introduction

    Am I interested! You bet!!!! I already did a (static) volcano cake for my son's fifth birthday, but his best friend was out of town so I promised I would do it again. All I managed was clear red candy designed to look like spewing lava. I haven't even read all your instructions yet, but I am SOOOOOOOOOOOO interested in your spare parts. I can't tell from the comments below whether someone wants the stuff yet. hope I'm first !!! I have some question about the shipping cost, but surely I can manage.

    samandodave spencer

    Reply 12 years ago on Introduction

    it looks to me like it is a drawer and i agree with exponent about it being soo koooool!!


    6 years ago on Introduction

    AMAZIN! i need one for my 11th birthday! its so cool. my friends will love it! ill ask for help from my dad, i think hell love this instructable! :)


    7 years ago on Introduction

    This is amazing. Wow, fantastic job. After my own heart, but this...this is beyond my scope. I hope your son knows what amazing parents he has that would go this far for him on his 5th birthday. Kudos.


    8 years ago on Introduction

    I am divorcing my parents, they should be ashamed at not having made me such an awesome cake for my fifth birthday. Very good effort, I hope your son remembers to do this for his kids when they turn five!


    9 years ago on Introduction

    1. i dnt call it a bit nuts..... i call it "SO FREAING INSANE U SHOULD BE COMMITED!!!' 2. $200??!?!?!?!? are u serious? talk about a waste of money! jeez! ever heard of the global unequal distribution of resources??? ure making exploding cakes wen ppl in 3rd world countries can barely survive bcos their so poor!, fine, i, myself am a bit shallow, i like pretty cakes, but $200 on an exploding cake? that is just too. far.

    3 replies

    Reply 8 years ago on Introduction

    You have obviously never seen the price tag on a standard wedding cake. Besides most of that cost is reusable. Please next time you wish to protest wasteful actions go to Al Gore's newest house.


    Reply 8 years ago on Introduction

    You really need a nice warm glass of shut the hell up. This cake was awesome. $200 is a small price to pay for an epic birthday for your child. Bravo to the parents. You: Plz die. Kthxbai.


    Reply 8 years ago on Introduction

    wow thats harsh. i thought the cake was awesome, im glad she had the idea. its always nice to see whats possible dont you think?


    8 years ago on Step 7

    Nice! The only heresy is "to reduce the volume of cake". Gasp! Yes it will be hard to top this. Maybe a glow stick in there somewhere for the glowing part of the lava? This even out does those Ace of Cakes guys. :-)


    8 years ago on Introduction

    This rocks. Anyone that undermines a homebuilt effort like this needs their medication titrated. Nothing done for a child is wasted, and people that live with actual children (rather than a collegiate study) applaud your efforts. And I thought the cake was a lie! Bravo