Rog8811’s managed to pack a green laser diode, mirrors, motor and battery into the slender form factor of a Zippo lighter – resulting in an extremely portable pattern projector. Very cool, and as you might imagine it involve a appropriately delicate construction –
For a spirograph pattern to be produced a minimum of 2 rotating mirrors are required. These were cut from an acylic mirror tile, it is important to get the hole dead centre, to do this I drilled a 0.5mm hole into a piece of 7mm diameter brass, stuck the back of the acrylic to this and turned to size in a lathe, (once stuck to a mandrel you can carve the mirror to size with a craft knife). Then use a pin chuck to drill into the acrylic from the back.