Summary

Scale the rail to the length you require and print as many inserts as you require.

Print Settings

Printer:

CR-10S

                                            <p class="detail-setting rafts"><strong>Rafts: </strong>                     <div><p>No</p></div></p>                                                                                <p class="detail-setting supports"><strong>Supports: </strong>                     <div><p>No</p></div></p>                                                                                <p class="detail-setting resolution"><strong>Resolution: </strong>                     <div><p>.2</p></div></p>                                                                                <p class="detail-setting infill"><strong>Infill: </strong>                     <div><p>30%</p></div></p>                                                        <br>                        <p class="detail-setting notes"><strong>Notes: </strong>                    </p><div><p>PETG worked great for this design. I have not tried PLA, I have my doubts that PLA would be strong and flexible enough for repeated use.</p></div>

Post-Printing

With a utility knife, shave down any parts that wont slide or are too big to fit a socket.
Epoxy the caps to the ends of the rail after installing inserts.

Sliding Socket Rail - 3/8" drive