Hexagonal Mirror Array Hides Hidden Message

[Ben Bartlett] recently got engaged, and the proposal had a unique bit of help in the form of a 3D-printed hexagonal mirror array, whose mirrors are angled just right to spell out a message with the reflections. A small test is shown above projecting a heart, but the real deal was a bigger version reflecting the message “MARRY ME?” into sand at sunset. Who could say no to something like that? Luckily for all of us, [Ben] shared all the details of what went into designing and building such a thoughtful and fascinating device.

Mirrors on the 3D-printed array are angled just right to reflect light into a message.

Essentially, the array of mirrors works a bit like a projector. Each individual reflection can be can be thought of as a pixel, and the projected position of each can be modified by the precise angle of each mirror. With the help of some Python code, [Ben] calculated the exact angles needed to spell out “MARRY ME?” and generated the necessary 3D model. A smaller-scale test (shown in the header image above) was successful, and after that it was just a matter of printing the array and gluing on some mirrors.

Of course, that’s the short version. In practice there were quite a few troublesome issues that demonstrated the value of using early tests to discover hidden problems. For one thing, mirror angle and alignment is crucial, which meant that anything that could affect the shape of the array was a potential problem. Glue that expands or otherwise changes shape as it dries or cures could slightly change a mirror’s angle, so cyanoacrylate (CA) glue was preferred. However, the tiniest bit of CA glue will mess up a mirror’s surface in a hurry, so care was needed during assembly.

The gleaming hexagonal mirrors are reminiscent of the James Webb Space Telescope.

Another gotcha was when [Ben] suddenly realized, twenty hours into printing the final assembly, that the message needed to be reversed! As designed, the array he was printing would project “?EM YRRAM” and this wasn’t caught during testing because the test pattern (a heart) was symmetrical. Fortunately there was time to correct the error and start again, but it was close. [Ben]’s code has an optional visualization function, which was invaluable for verifying that things would actually turn out as expected. As it happens, the project took right up to the last minute to complete and there wasn’t quite time to check everything 100% before the big moment, but it all turned out alright. What’s life without a little mystery and danger, anyway?

The pictures are great, but you won’t regret taking the time to read through the project page (don’t miss the annotated Python code) because [Ben] goes into just the right level of detail. The end result looks fantastic, and makes an excellent keepsake with a charming story.

Man Proposes To Girlfriend With An Arc Reactor


Thinking long and hard about how to propose to his girlfriend, [Ed] hit upon a great idea: use an arc reactor as the ring box, with enough LED lights to outshine all but their love, and servos to present the ring and tug at the heartstrings.

[Ed] set about giving his now-fiancé from his arc reactor heart by building a simple circular arrangement of adafruit RGB LED strip and an Arduino. There are two modes for this arc reactor: a light up mode that simply looks awesome, and a ‘ring mode’ that uses two servos to open the front cover and bring the engagement ring into view.

After [Ed]’s fiancé said yes, the cover in the center of the arc reactor closes for its continued use as a desk ornament. You can check out [Ed]’s proposal contraption in action after the break.

Continue reading “Man Proposes To Girlfriend With An Arc Reactor”

Tying The Knot With MakerBot


De Beers would have you believe that only diamonds will do, but hackers are hardly ones to follow convention. How better to say “I love you” than with a MakerBot-extruded black ABS engagement ring? [Adam Elkins] did just that, creating the design with a combination of GIMP, SketchUp and Blender, then producing the final output on a MakerBot at Philadelpha hacker space Hive.

From the steampunk wedding at the 2008 Maker Faire, to the science-meets-romance web comic xkcd, hackers certainly have some unique ways of expressing their devotion. What are some of the wildest or most charming that you’ve seen? Comments are open…speak now or forever hold your peace.

Oh, and the engagement ring? She accepted. Congratulations to the lucky couple!

[via MakerBot blog]