Expanding Mound

About: Student at Iceland University of the Arts

The expanding mound just looks like a normal mound. However when you get close to it something happens. It expands and lights up!

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Step 1: Step 1: the Mechanism

The mechanism is built on the Hoberman Sphere, I found this model on Thingiverse by user SiberK. I did some adjustments in Fusion 360 to make it bigger so I could lasercut the links out of 3mm masonite, the original has 2mm 3d printed links.

3D-print 18 cross links

Lasercut 60 links out of 3mm masonite

The holes in both the links and 3d crosslinks are designed for 3d printer filament to act as a pin.

When locking the links together with the filament, melt one end of the filament pin. Then you melt the other side when the links are linked.

Use the picture I included for assembly and make a dome; like you see on top of my friends head.

Lasercut 4 racks, 4 sliders and 1 pinion out of 4mm MDF (the pinion is designed for the geared motor I had, it should be changed if a different motor is used)

Make the racks and sliders double in thickness by gluing together.

I have a picture of the rack and pinion setup. Have in mind that the motor is driving the gear, everything has to be aligned according to the motors position.

Step 2: Step 2: the Electronics

Wire everything according to the pictures.

The limit switches are positioned according to the racks when the Hoberman dome is either closed or open.

Glue the LED strips down and put a piece of frosted plexi glass over it.

I use 2 dc power adapters to drive this thing. 12v for the LEDs and 9,5v to drive the arduino.

Step 3: Step 3: the Code

Use the moundpir if you wand the movement to be triggered by a pir sensor.

I also have code for a loop that doesn't need the sensor.

Motorspeed in the code is set at 70 of 255 now. I am using 9,5v 1.2 amp power adapter to power the arduino, but when I use the usb cable 70 isn't enough to drive the motor. So when testing everything out with the usb cable, have the motorspeed at 255. Do not have motorspeed at 255 when using power adapter it goes way too fast, and can destroy the rack and pinion.

Step 4: Step 4: the Look

Find a plastic dome roughly the size of a closed Hoberman dome.

Cut it into 9 pieces and glue to the Hoberman sphere.

Then glue a thin layer of foam on top of the plastic.

Paint the foam and let it dry with the Hoberman dome closed so it retains its shape.

Glue moss on top of the foam.

Finish everything up.


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    5 Discussions


    13 hours ago

    I really like this. It brought a big smile to my face. Fantastic creativity, and the addition of the gong at the end of the video made it that much better. Voted for you! Well done.


    18 days ago

    Really cool. Voted for you!


    27 days ago

    This is interesting. Can you explain the purpose behind this creation? (What was it made for, etc?)

    2 replies

    Reply 27 days ago

    Hi, thanks for the comment. This was a school project (I study product design). We were supposed to make interactive nature. The creation doesn't have a clear purpose. But I like the fact that when I displayed this project in school people were speculating what it really was. But essentially this is an art project.
    Best wishes Arngrímur


    Reply 26 days ago

    Very cool! Thanks for the explanation! : )