Most DIY projects never go beyond what’s essentially a prototype stage—they’re one-off affairs that don’t have to be cost-effective or easy to use.
But after a bunch of your friends say, “Gee, I could use one of those,” it’s time to consider producing your project on a larger scale. It’s also time to rethink the entire project: What works for a single build often doesn’t when you have to do it hundreds or even dozens of times.
I got a sense of this recently when my son and I built a high-powered replacement for the Wii sensor bar. Nintendo’s own sensor bar, which is actually a pair of infrared emitters that the Wii controller uses to determine which way it’s pointed, isn’t much good beyond 3 meters. We created a bar that has nine high-powered IR emitters. (Actually, we built two bars, one for each of us.) We liked it so much we knew others would too, so we launched a Kickstarter project with the goal of producing at least 100 pairs. Kickstarter is a way to fund projects in which the money comes from potential customers instead of a bank (see “Getting a Kick Start” for more about it).
When you create a Kickstarter project, you need to figure out the pledge levels and exactly what the pledger gets for his or her money. Essentially, you’re figuring out the selling price, as you would with any product. It turns out there’s a lot to consider.
First, there’s the matter of component costs. Large-scale production saves money on both unit costs and shipping. The printed circuit board for the MegaBar (as we called it) ran about US $13, using BatchPCB (which I described in an April 2010 article, “Build a Custom-Printed Circuit Board”). But for 200 (two boards per pair), the cost dipped below $2, an $11 savings. While things like switches and LEDs don’t go down as dramatically, savings of 25 to 50 percent aren’t uncommon.
By the way, for those off-the-shelf components, I avoided eBay as much as possible. All too often you find a bargain that’s not available the next time you need it. Industrial suppliers, such as Mouser Electronics, keep large stocks of components available and will tell you how many they have on hand. Mouser, with an easily searched website and online data sheets for pretty much everything it sells, is especially nice.
Once you know your component prices, consider the packaging. This is really just another component, but because it comes last, it’s often overlooked. We wanted to keep the bar small, but the device needed some extra room for thermal dissipation—the driver chips can get quite hot. We settled on cases normally used for pagers, which had the added benefit of having internal standoffs that could be used to secure the board.