While the film's producer discussed the variety of lighting animations needed for each scene, I sketched a series of front panel arrangements to help draw out the requirements for how the model's lighting would be controlled. Here's the one we settled on.

The controls of this conceptual drawing were grouped logically by required functions (from left to right): Global Controls, Ring Patterns, Portal Patterns, and Spots Color. Controls were arranged with the most-used controls on the right side of the panel since the operator is right-handed. The power switch was placed away from the other controls to prevent accidental operation.

The Global controls include master brightness and speed for all animations as well as the controller's primary power on/off switch. Each of the other functions have separate on/off switches to allow any combination of the functions to be operated simultaneously (that also created some interesting software challenges). Each function has a variable control knob that selects a pattern or, in the case of the spotlight function, varies the color.

There were no indicator LEDs on the conceptual version of the front panel. It was thought that the switch positions would clearly show the status of each function. That's something that changed during the evolution of the design.

The next step in the process was to determine the physical dimensions of the control panel. Spacing between switches and potentiometers should 1) appear visually balanced, 2) accommodate the operator's fingers, and 3) provide enough room for the knobs, connecting wires, and the component itself.

A grid was drawn over the conceptual drawing to get an idea about physical size. Next, a graphical rendering of the final front panel was made to obtain the producer's approval of the look, feel, and functionality of the controller.

Evolve the Design

The panel design for this project had to change to accommodate an available enclosure and panel size. The overall layout of the final version (on the right) is very similar to the original concept, but the iterations made it smaller, simpler, and more consolidated. The design evolution also introduced a way to incorporate color-coded activity LEDs to make it obvious which function is active.

Once the design is completed, component layout can commense. To do that, we're going to need an accurate drawing so that we can drill the enclosure's front panel for those LEDs, switches, and potentiometers.

Produce the Panel Drilling Guide

After the conceptual design is finalized, overlay an accurate grid to determine hole placement and to guide the panel machining process. The drilling guide can be drawn by hand, designed in a CAD tool, Photoshop, or even PowerPoint. Accuracy is important since we'll be applying a label layer that will need to line-up with the enclosure's panel holes.

• Use the drawing tool or method that is most familiar to you and that can print out accurate copies of the guide on paper.
• To speed up the drilling process, list the diameters of each hole on the guide.

Some components employ integrated mechanical index pins or tabs to prevent the components from changing orientation during use. Another benefit of using index pins when fabricating is that the component's mounting nut won't have to be over-tightened to secure the component, avoiding label and panel warping. Both label attachment techniques in this guide will disguise the index pin holes so that they won't show on the the finished panel.

Determine Component Placement

It's a good idea to check your panel layout with actual components. In this photo, a drilling guide was placed on the front of the enclosure, then each switch, potentiometer, and LED bezel was positioned to confirm the look and feel as well as the wiring clearances needed for electrical connections. Use a few globs of blue tack to stand up components in their typical operating orientation to complete the visual mock-up.

Many software CAD tools have 3D features to assist in component placement and clearance tests for printed circuit boards and 3D printing. With the addition of a few custom footprints for panel-mounted components, you can use the tool for designing front panels. Here's a rendered KiCAD example of the panel layout for this project. The underlying 2D model can easily be printed and used as a drilling guide.

Next, let's have a short discussion about the two labeling methods.