This is my first 3D printing project. It's a so called ruler plotter. The arms connect to each other with 688-sized bearings (16x8x5 mm). The bearings fit on the 8 mm pegs seen on the two arms to the right. The two arms to the left have 16 mm holes with a cup-like structure, which fit over the bearings. The wafer pattern in the arms are holes and is there to reduce weight and still secure a stiffness.
Since I haven't done 3D printing before, I'd like to know if there are any obvious faults in my design. There are no printing over cavities, except the cups, which have small lip, which turns slightly over the 16 mm hole. The cup looks like this:
Here's another realization of the ruler plotter, where stepper motors are used, but I'm planning on having hobby servos instead. The bearings will hopefully make the arms move more smoothly.