Link for RC vehicle suspension

Print one or more of these (45mm provided, use f3d file to customize length) for RC links (crawlers, etc)

Using 16 mm M2 screws, drop one into each side. Fill gap with a short piece of 1.75mm filament and glue or melt it in. Alternatively, wrap in heat shrink. (photos show examples of different approaches, the melting doesn't produce what I'd call a pretty finish, but that could just be limitations in my own skillset)

Note that the total length of the link depends on the length of screws used and the length of the ball joints, so consider what you need, and alter the design accordingly. 

Also, attach the ball joints BEFORE gluing in the screws as they spin freely and are difficult to screw in otherwise.

Crude, but it works :D