This candy bowl growls and moves as if there is a creature tunneling through the candy.
Step 1: Parts and Tools
2x Candy Buckets
Small Strip of Wood (not pictured)
#8 screws and bolts (not pictured)
High torque continuous rotation servo motor
Small micro-controller with headers
4x AA battery holder and batteries
Scraps of wire
Wire nuts (not pictured)
Hot glue gun
Step 2: Constructing the Bowl
The upper candy bucket holds the mechanism and the candy. All that is needed here is mounting the servo motor. Note that the motor pictured here is not the one that I ultimately used, however the size and mounting holes are mostly the same between models.
1. Using the hot knife, cut out a rectangle to house the servo.
2. Drill holes for the servo mount screws.
Lower Candy Bucket
The lower candy bucket is the base, consealing all of the electronics.
1. Cut a large rectangle in the bottom.
2. Trim the sides, leaving 3-4 inches.
3. Cut a small rectangle for the switch which gets mounted later.
Assembling the the bucket
1. Attach the upper and lower buckets together to form the bowl and base with a liberal amount of hot glue.
2. Feed the servo wire and servo into the opening.
3. Using #8 screws and nuts, bolt the servo in place.
Step 3: Constructing the Movement
Ball and Roller Assembly:
1. Make the lever from a scrap of wood about 1 inch wide and a little shorter than the radius of the bottom of the bucket.
2. Drill holes to mount the ball roller and affix it with screws.
3. Drill another hole to mount the wood knob and screw it on the opposing side of the roller.
4. Attach a horn to the servo and hot glue the lever to the horn.
Only the inner hoop is needed for this; the fastener of the outer hoop gets in the way.
1. Fit check the hoop to make sure it is the right size. It should rest in the bowl at the level of the top of the wooden knob.
2. Put an old shirt in the loop, stretch it tight, and fasten it in place with the outer hoop.
3. Cut the shirt, leaving about 1 inch margin.
4. Hot glue the shirt by folding the remaining fabric over the inside hoop.
5. Remove the outer hoop.
Step 4: Electronics
This is a quick and temporary wiring job that will not survive rough handling. The wiring is fairly simple here so I am not providing a schematic. On some micro-controllers, it would be sufficient to wire power through the switch, however the trinket takes a moment to boot and I wanted the switch to be instant.
The switch, wire nuts, and micro-controller are hot glued in place. The battery pack is duct taped to make swapping batteries easier. Note that this is not the battery pack linked on the parts list, but I wish it was. The linked battery pack has a smaller profile and a power switch but is otherwise the same.
The arduino project is attached. The logic could be ported to other controllers easily. The whole thing amounts to: when the switch is pressed, send rotation pulses to the servo, otherwise, send nothing.