Halloween Lolly Launch Tube

Hi thought I would share my Halloween project a ‘Lolly Launch Tube’. Basically it 1000x100mm PVC tube, a 45degree angle connector, programmable RGB strip, PIR sensor, 12v large solenoid, 5v relay and Raspberry Pi PIco W micro-controller.
Not being a mechanical(or any kind of) engineer it is a bit rough and ready. The trap door is from MDF and ply wood, the activating arms are made from 10x3mm aluminium strip drilled with 3mm holes to lighten same.
Also 3/8" threaded rod for the fulcrum. The other fittings are from the same aluminium strip, brackets to hold the tube to the base board, connecting bracket on the trap door and the fulcrum bracket.
The Pico has been programmed to run an RGB light show until the solenoid is activated by an ISR triggered by the PIR. When triggered the trapdoor is dropped sending the lolly down the the tube to the eager Trick-or-Treater. Additionally the light show change to a three led chase sequence down the tube.
Things I have learned:-

  1. I am not a mechanical engineer.
  2. The PIR is not the most reliable sensor for this application. A microwave sensor is possibly a better choice.
  3. A feed mechanism would much better solution than the trapdoor. Limited time, limited mechanical skill and the need accommodate different size and weights of lollies make a hopper system impractical. I have in mind some of conveyor system.
  4. Sound effects, the silent device lacked a dimension. Appropriate sound effects will enhance the experience.

What does it do? Does it dispense candies?

Yes, Covid safe contact less sweet distribution.

Hi Adrian,

That’s an awesome project. Did it have any problems dispensing any particular type of lollies?

A great alternative in a Covid safe world!



Fun size and individually wrapped lollies were OK, Chuppa Chups zoomed out and over the stop I had in place otherwise no problem. Packets of sweet like little packages of Skittles would get stuck at the top of the tube, however, a gentle they were on their way. I am just thinking through how to implement a conveyor system as a better way to deliver the lollies, make it more automatic.

Hi Adrian,

I thought different lollies and packaging might interact with your system in different ways.

As for automation, I can envision a screw conveyor/elevator system as being an interesting way to function independently, especially if used with a hopper system. You could use a stepper motor or standard motor with enough torque to dispense a fairly accurate amount too.


I have thought about a hopper system, however, different sizes and weights make that too challenging for my limited skills. A belt or chain conveyor seem the most feasible. Particularly if the conveyor uses buckets or skips. The challenge selecting the right motor and gearing.

That’s good. I recovered from covid very recently. I am glad to see that you still think about covid precautions.