This is a secondary mirror holder upgrade for the Celestron FirstScope Newtonian telescope (76 mm aperture). This telescope is known for sometimes having the secondary mirror very unaligned. Furthermore, the original holder collimation has a very low movement range.

This print is a fast and easy upgrade. It is designed so the secondary mirror and its support fit inside the printed piece. It adds about 3mm length, which in my case was almost perfect.

The piece is a tight fit. If yours doesn't fit, use settings as horizontal expansion or increase the piece size until it fits your mirror.

You need:
3x M3 screws (original screws work fine)
3x M3 nuts
1x Pen spring
Hot gun (or other means to secure the mirror, improvise)

Instructions:

-Put the 3 nuts in their inserts and insert the screws.

-Insert the secondary mirror into the printed piece. Check how it fits! In my case, the holder was so unaligned that the "bump" between the screw holes was out of center and didn't allow the mirror to totally fit inside, so i cutted that bump (I used a tin solder to carefully melt it away).

-With the mirror side oriented to the bottom, use both holes at each side of the printed piece to insert hot glue inside the piece and secure the mirror.

-Put the spring in the central hole between the screws, and mount the printed piece into the "spider"/holder.