The RepArm mk1 is a really low cost, cartesian robot arm using RepRap components. Most of the parts can be printed, and only a few belts, steppers and linear rails with bearings are needed.
The total cost of the robot arm if buying parts is just about $175. Most people would be better suited finding an older RepRap 3d printer and repurposing the motors, pulleys and linear rods and bearings, which makes the arm very cheap and provides a good way to experiment with a simple robotic arm system using the cartesian system which is much more inituitive to work with than a SCARA or articulated robot arm.
Now, obviously the RepArm mk1 isn’t the most rigid robot – surely a lot of improvements could be made to the design, but it is difficult to create something very accurate and rigid if 3d printed parts are to be the main structural element.
View the RepArm mk1 as the middle ground between a flimsy RC-servo driven arm and something like a Dobot or a Makerarm. It doesn’t rival the Dobot in rigidity and precision, but it is a lot cheaper and, as mentioned, almost free if you can find just a few parts.
The RepArm mk2 will likely be a SCARA-configuration arm using off-the-shelf (but still affordable) components with the goal of making something that is slightly more expensive but still much more affordable and much more open than existing projects.