A friend at our makerspace made a little engraver with some dvd burners, following this Instructable http://www.instructables.com/id/Pocket-laser-engraver/ (working surface : a bit more than a business card)But I wanted to give it a nice structure (and maybe an enclosure later), this first version is even foldable :)More pics and progress on our wiki : http://wiki.nybi.cc/index.php/Pocket_Laser_EngraverThe spacing between the little smooth rods in the salvaged DVD can vary (in our case it was approx. 47mm), so you may have to measure with a caliper what's yours and tweak the source file.Beside that, this version was made to be cut from 3mm material and assembled with some printed parts and M4 bolts (I had a bunch of M4x16, but a little shorter would be better).Unscrew needed parts and put everything on the structure (reuse the little bolts for the motor plate, or take M3 and file holes to fit). Alternatively you can replace the 16 bolts and 8 printed parts that hold the smooth rods by 8 zip-tie.At the end you'll have an ultra-portable-laser-engraver perfect for small demos and little jobs :)