Shooting Stars

This is an all-DIY project that provides an opportunity to use a 3D printer to create a nifty lighting effect! It's not a hard project, but it's a bit of a time-consuming one depending on how many "stars" are incorporated into the display. For this project, the author designed a 24-star line with stars approximately 1 foot apart. The goal was to create a display piece that could be wired from the ground up to a larger main star mounted in a tree or on a garage roof so that it would appear like an eye-catching "swoosh" of light rising up to the main star. Therefore, each star in the line also needed to have individual control.

It was thought that while a string of pixels could certainly be used to accomplish the animation function, the individual pixel bulbs weren't large enough to be truly eye-catching. But pixel technology could certainly be used -- just not with individual bulbs. And since color wasn't important, a project similar to the monopixel candy canes (How-to is HERE) seemed appropriate.

• First, a star had to be made. This proved to be quite easy on Tinker Cad, which provides a basic star shape. It was enlarged to approximately 4" across nd the center raised. Then it was duplicated on the screen, the duplicate was reduced in size by about 2mm in all directions, set to be a "hole" and simply merged into the first star. This resulted in a star "half-shell" that when two stars were glued together, would provide plenty of room for electronics inside. For the 24-star display, 48 were required. (Note: printing time was a bit over an hour each which is why this project takes some time... The STL file for this star is at the end of this how-to.)

• The electronics inside the stars were simple: five white LEDs soldered onto a two-sided piece of spare PCB stock. Anodes soldered to one side; cathodes to the other and a lead wire soldered to each side -- all 5 leds would be in parallel. The wire chosen was a pair of wires stripped from a length of CAT5, chosen for low-cost, it is easily able to handle the tiny current needed to illuminate the leds but the small gauge of the wires made it quite invisible, too.

• A prototype star was assembled and tested for feasibility before investing more time in the project. Prototype video: HERE The protype electronics were also tested without the star shell and it was decided that the LEDs' lenses were too directional and more light would be captured with the star shell than without it.

• Being adequately bright, two more stars were printed and one complete segment of 3-stars wired to an inexpensive WS2811 board designed for square-base pixels using the board's RGB and +V connections. The square pixel board has all the necessary components for LED current control while also supplying 18.5ma of current to each of its three outputs. A video was made of the actual prototype test: HERE A second video was made viewing from a 25' distance in darkness and we liked the result: HERE so we decided to start printing more star shells.

• We determined that some sort of wiring harness might be helpful to make this project a reality. And since it had been decided the stars would be 1 foot apart forming a 24-foot line of stars, this required eight 3-foot long segments comprising one square pixel board and three, 5-point LED boards were needed. The segments would then be attached together to form the 24-foot line. While the star shells were being printed, a wiring harness was constructed. We chose 4-conductor telephone wire for the main cable primarily for its strength but also because it was a smaller diameter than CAT5 and might be less visible.

(Note: the project stalled-out after 17 shells were printed because of problems with the printer. After the problems were resolved, printing resumed...)

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more to come----