A slightly bigger spy-mirror object for events, like the upcoming Chaos Communication Camp, first time going outdoor. Tested already at Make Munich, Laserworld of Photonics and Makerfaire Berlin within our Personal Photonics booth.

It uses a bunch of 60 LEDs/m stripes (roughly 30m), few square meters of spy mirror acrylic (and a little bit of normal mirror acrylic for the bottom as well as some MDF for bottom and connector at the tip), square hollow aluminium rods (above 10mm width for the stripes), some wires, arduino and a strong power supply (60W @ 5V). The acrylic sheets are screwed on the aluminium rods with small metal screws, and some longer nuts and screws M5 size.

Transparent tape for fixating the stripes and black tape conclude the parts list.

For rebuilding there is still room for improvement, it was just the first try with improvements after each event.

Step 1: Basic Construction

Main thoughts flow into the mosaik construction of the sides (see svg-file) to get the obelisk transportable, in this case by dividing the sides into smaller parts as 50cm*30cm, resulting in a nice transportable box.

These sheets where then lasercut.

Construction frame consists of a baseplate (consisting of 4 52cm*26cm plates, lower ones out of MDF, the upper two out of acrylic mirror, which are connected over cross into a 52cm*52cm square), aluminium rods on the edges until a 30cm*30cm lasercut square connector (1 cm height, here done out of two 5mm acrylic sheets), with four additional rods both on the bottom as well as for the tip.

Into the longer rods on the side (2,4m long) nuts are hammered in, such that both bottom as well as top lasercut squares could be connected with the rods through screws. The whole frame structure is then covered inside with the LED stripes on the inner edges, glued onto the stripe with both the included doublesided tape as well as secured with transparent tape wrapped around the rod and stripes. Same goes for the tip regarding the stripes, which are connected simply with tape with the rest of the structure, with each LED strip connected with wires with the lower ones.

Each Strips data input as well as power supply is routed out of the obelisk at the bottom, to both power supply as well as an arduino for data (all four edges are supplied with the same data in parallel).

Afterwards, the spy mirror sheets are drilled and screwed onto the frame, with small gaps in between for slight movements.

obelisk.svg
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Step 2: Finishing Up

For nicer look, the connecting borders of each spy mirror sheet are covered with black tape. On the inside, the glue side would be white, which harmonizes good with the white LED housings and strip color.

The power supply and Arduino can be hidden within a box bellow (using as sort of socket, e.g. in our case two of the Zarges boxes used for transportation, covered with black textile. But a dedicated socket would look great, maybe we get it done for the CCCamp).

Programming is kept simple, we used just the FastLED library and the ColorPalette example, which looks great.

As further improvements we separated later the 2,4m rods into three parts (better train compatibility), with inserted smaller aluminium rods inside as a connector such they could be stuck together, with pinheader for electrical connections.

Of course, one should take care that the spy mirrors are transported covered in textile or similar, to prevent damages on the mirror coating. Furthermore, we got some problems with electrical connection due to transport and quick setup, it also looks nice if some stripes won't work.