Sketch out idea
We drew it out first on paper, and then figured that it had to be much bigger than last years version; especially if it was going to throw up candy on the trick or treaters!
Since we didnt really know what we were doing we ended up using PVC pipe because its cheap and easy to cut without much mess. To make it mobile we screwed it into a cheap dolly and added a sheet of plywood to make it completely flat. Then we secured the bottom of the creeper frame to the board as well.
The other good thing about PVC is that you can completely take it apart which makes transporting easier. We used 3/4" diameter which is strong enough for this application, make sure to get the thicker kind. Didnt know they had thicknesses so make sure its not paper thin which could affect the stability of the structure. The rear is designed to be a shelf for future components like a computer or candy storage area.
So with our initial concept the creeper needed to do a few things:
1.) Make sounds
2.) Eyes light up
3.) Dispense Candy
So for the Remote to control all this we used:
USB POWER > FORK > BUTTON > WIRELESS TRANSMITTER
For the receiving end:
USB POWER > FORK > WIRELESS RECEIVER >(channel 2) > TIMEOUT > BRIGHT LED > WIRE > DC MOTOR > SPLIT WIRE (1 side to next motor with other to lights) > DC MOTOR > (WIRE x2 > LED x 2 for the eyes)
WIRELESS RECEIVER (channel 3) > MP3 Player > SPEAKER > SPEAKER (I salvaged 2 speakers from a tv I found in the trash and they worked great with the bits)
We also made a flap that could help push candy which kinda worked using:
USB POWER > WIRELESS RECEIVER (channel 1) > PULSE > INVERTER > SERVO > INVERTER > SERVO
To get the servo arms to quickly shake we used the pulse bit. To get the sero arm positions moving in the direction we wanted we used inverters.
Build out candy dispenser
We went through many iterations on how to actually dispense the candy. The challenge was to restrict ourselves to primarily using the bits we had without modification all while keeping it as simple as possible so others could replicate. We tried using a couple of lego bulldozer scoops attached to a large gear and that kinda worked but was not strong enough when the candy was fully loaded so we went back to the drawing board and came up with using a conveyor style system which ended up being more reliable. To help the conveyor out we added nubs to the tracks at various intervals to help move the irregular shaped candies along.
Test and troubleshoot
We failed many times with different candy feed mechanisms until we came up with one that worked most of the time. The great thing is that since we used cardboard and PVC for the structure is that its easy enough to pull out the whole unit and try out different ideas.
Using cardboard and scissors/xacto knife we cut out the skin.
Next we painted it with spray paint
After it dried we attached the pieces to the skeleton with Velcro so we could disassemble for transport and troubleshooting.
Finally for the face we cut out the shapes for each area out of clear plastic (the kind you get on toy packaging).
Next using black nylon leggings we stretched and hot glued the nylon to the plastic and then the finished pieces to the face plate. To help flatten out the hot glue we used the wax side of the used up Velcro strips as it wouldnt stick to the glue but any wax paper should do.
Now test the whole thing again and make any adjustments now that the skin is on. We ended up having to add some more cardboard to the mouth area as candy was starting to get stuck at times.
We had added a GoPro camera to the nose but didnt end up using that since it was too dark for what we wanted.
Trick or Treat!
Bring out the creeper and setup a table with an optional bowl to catch the candy. The lights on the table are a separate project that I will post up, but basically its an IKEA cabinet door with glass, carboard, Arduino bit, Proto bit and a NeoPixels compatible light strip (60 lights)