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Standardised Filter Case


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I’ve recently gotten Shadowfoam and made an eyepiece case/tray.  Not a huge amount of space in my tray and in trying to fit everything in I noticed 2 things about my filters:

  1. The boxes are huge.

  2. The boxes are difference sizes.

Being blessed with a 3D printer I downloaded and STL for a case which is round and screws together.  However because of the male thread it’s a bit of a faff getting the filter out and I managed to get a thumb print on my UHC filter.  I did like the embossed lettering on top though.

  Spent most of yesterday cleaning out the bunnies and designing a better case in Fusion 360 and came up with this design:

  • The wings and cuts allows you to easily grab the filter without risk of thumb prints.

  • The treads are matched up so that when it is tight the wings of the top and bottom piece align and are held closed by friction.

  • It’s pretty small so won’t take up acres of real estate in the eyepiece case.

  • The embossed lettering allows you to easily feel what the filter is in the dark if you have lots the same size.  The missus has a Cricut so I’ve ordered some glow in the dark vinyl so I can cut and stick lettering in it to make it more readable.
  • The design is relatively simple and can easily be modified for longer filters such and the variable polariser, or where you might have 2 screwed together for standard use.

Any thoughts?

prototype filter holder.JPG

prototype filter holder design.JPG

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Posted (edited)

Cheers guys. I'll make up some stl's for different lids with some common filter types.  

EDIT:  I'm going to chonken up th thread and then upload.

Edited by Ratlet
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The trouble with having a 3D printer is the temptation to refine a design...

I've changed the thread so that it has a quarter turn rather than multiple turns.  This also means that it will secure either way and should be less fiddly at night.

Also adding some cutouts to prevent it turning beyond being in line and I'm getting it so there is embossed text on the long end so I can see which filter is which whilst they are in the case.  Glow in the dark viny should arrive tomorrow so I can see how the text looks filled in.  The wife was unimpressed I used loads of the rainbow pla so I've now ordered some Matt black.


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Been through a few iterations of the design.  Just about there.  Adjusted the depth so a craft foam insert can go in to help protect the filter.  Now includes a stop point to prevent over extending, but need to adjust the design so that friction will hold it shut.

It works as is with a small bit of flocking material stuck to the case, but would like to do away with that.  Experimenting with glow in the dark vinyl for the text in the recesses


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That's me done.  I decided to do away with the recessed text and instead go for a recessed block instead.  Makes it much easier to write/stick things to.


  • 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.
  • Recessed section on lid (50mm x 18mm) and on long axis of case (14x18mm) to allow writing of contents with an element of protection.  Personally I’m using glow in the dark vinyl sheet cut to size in case I drop the case in the dark with a coating of clear nail varnish to seal.
  • 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.
  • Internal stops to prevent the case being turned past the closed point.

I’ve designed and tested this with esun PLA using prusa slicer default 0.15mm (Quality) settings. Other filaments will probably work. You might find the case is too tight or too loose though.  I’d recommend using fine sandpaper to remove material or to use some of the self adhesive flock to add material for adjustment.  stl's are here.


filter holder.JPG

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