Me and my buddy are trying to raise funds for a compact stepper driver board, uStepper. To give some examples on how you could use the uStepper, I did a very quick design of a robot arm. So it may not be the smartest design, but it's a good basis for derivatives! VIDEO: https://www.youtube.com/watch?v=1ebjdsye-PE Please visit http://www.ustepper.com/ where there is also a link to the Kickstarter campaign! Detailed instructions and a BOM will be made available once the Kickstarter campaign has been funded! NOTICE: The gears for the arms have been updated 27/8 16:50 DK time! The small gears where mirrored in the first upload, sorry for any inconvenience this might have caused even though it says work-in-progress! The gears are modified versions of the "OpenSCAD Herringbone Wade's Gears Script" "(c) 2011, Christopher "ScribbleJ" Jansen" - So I cannot take credit for these well designed gears.You will need aluminum rod in both Ø 15mm (~13mm inner) and Ø6mm. Besides that, a couple of bearings are used: 4 pcs. 608ZZ 10 pcs. 624ZZ 2 pcs. 625ZZ The tubes were bought at the local hardware store called Bauhaus. The tube lengths for the two Ø15 are 170mm and 310mm, the Ø6 are 270mm, 220mm and 210mm (that is the lengths they are when I cut them - not including the printed ends). But alle the lengths are derived from what I thought worked. I have not done any kinematics/calculations on this, so it may not be the optimal lengths. M3 x 20mm = 24 (I cut them in length to fit - if it is necessary) M4 x 20mm = 4 M4 x 30mm = 1 M4 x 35mm = 1 M4 x 50mm = 1 M5 x 40mm = 1 M8 threaded rod 70mm or 65mm if it's a bolt M8 x 35mm = 1 All lengths are of the threaded part of the bolts - not including the head (but that is also what's normally stated on the boxes you buy them in) Besides that you will need nuts and spacers. Between the two main gears I used a lot of spaces to keep the apprpriate distance between the gears. I realize that finding some aluminium tube with inner diameter of 8mm would look better and do the job just as good.