Thingiverse is a great place to find 3D printable robotic parts. This arm works great for micro servos. Assembly of the parts is very simple but some modifications may be required to get everything working well.

Once the parts have been printed and the servos installed, your arm should look like this:

The square blocks that hold the servo horn still may need to be cut down to fit the horns that come with the analog feedback servos, as shown in this picture:

If the joints are slipping off the stationary ring opposite the servo horn, you can cut down an extra horn and screw it into the ring. This will keep the parts together nicely:

The legs of the base part are pretty short for the amount of weight and motion of the arm. I hot glued the base to a balsa wood platform to keep the arm stable when in use. Any form of additional base support will be great so the arm doesn't topple over.