Astronomy filter drawers (customizable!)

This model allows you to customize and print an astronomy filter drawer. While there are several really excellent designs out there already, none exactly matched what I was looking for. Specifically I wanted a 21mm filter drawer with M42 internal threads on one side and M42 external threads on the other - which could replace the 21mm spacer in my current ZWO ASI533 setup. This was also an excellent opportunity to learn OpenSCAD!

The attached OpenSCAD file allows you to easily customize a filter drawer and slider. Options include:

• Customizable drawer height 
• Customizable drawer diameter
• Internal or External metric threads on either side, with customizable diameter and pitch
  • See this website for a list of common astronomy thread diameter/pitch https://agenaastro.com/articles/guides/astronomy-threads-explained.html
• [Optional] magnet sizes (if you want to use small neodynium magnets to ensure filter trays don't drop out

Printing instructions:

• IMPORTANT: Layer height = 0.1mm. 
  • Larger layer heights are too coarse for the threads to work.
• Material: any rigid material should work (PETG, PLA, …)  
• I used 3 walls and ~75% infill for rigidity. This may be overkill. 
• Warning: expensive filters and cameras will be attached to this part. Therefore it may be wise to print a test version and destructively test it to ensure it can handle the weight of your setup.
• You are using this entirely at your own risk!

This design drew a ton of inspiration from the following three projects:

• https://github.com/alanzjl/FilterDrawer
• https://www.thingiverse.com/thing:4396710/files
• https://www.thingiverse.com/thing:4392304

Finally, many thanks to Dan Kirshner for his excellent thread module (https://dkprojects.net/openscad-threads/)