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...

smoke

erupt with lava

vibrate

and finally, make volcano noises.

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

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!