I was a bit annoyed with trying to fit my filters into my eyepieces case.  Every filter seemed to come in a different box which meant they could either float around loose or I’d need to make multiple different sized holes in the foam.  I decided this would not do. 

This case is designed to hold a 1.25” Astronomical filter.  The case design has a standard profile with different thicknesses to accommodate different heights of filter.  It has a wing and cut system which allows you to get a good grip of the filter without getting thumb prints on the glass. 

The design has been updated based on my own and others use to try and improve it.  This includes redesign of the thread to make it fit better and more consistently as well as removal of the recess on the top to make the print neater.  Prusa slicer can create negative space if you want to include your own recess for a label on the lid.

The previous design has been retained in a sub folder, but I don't recommend using it.  Due to the change in the thread the new deign is incompatible with the old one.

Features:

• 32mm ID internal cell for holding filter securely.  If you want it to be super snug you can add small strips of flocking material.
• ‘Wing and cut’ system internally allowing you to get good access to remove the filter without getting thumb prints on it.
• 1mm Internal rebate for foam insert.  I use +/- 2mm craft foam cut to a 33mm diameter circle stuck with glue.
• Range of depths to accommodate filters from 7mm to 23mm.  This includes the craft foam, so up to 25mm could work.  The largest case holds a variable polarising filter.
• Quarter turn lid which is held on by friction from the base and lid.  The lid can fit either way as the design is symmetrical.
• Designed to be stored with the long axis up in an eyepiece case (hence the recesses on the ends) to minimise space and make a simplified storage option.
• 10mm recessed dot in the base.  Again so that that I can put something glow in the dark in the bottom to help finding it in the dark.  This allows idntification of the bottom in the dark also.
• Internal stops to prevent the case being turned past the closed point.

I’ve designed and tested this with PLA and PETG at 0.15mm and 0.2mm quality and both work well.