Parametric (FreeCAD) lens cap generator

Since I've come across some camera lenses with missing caps, I've designed a #parametric model in #FreeCAD.

Just enter the filter thread size (and optionally thread pitch, spring width/thickness, and some other variables), and voilà: lens cap.

In a little more detail

1. Open parametric_lens_cap_no_numbers.FCStd.
2. Double-click on the vars spreadsheet.
   
3. Here you can find all the variables you can tweak. In most cases, it should be enough to simply enter the filter_thread_size of your lens.
   
4. Export spring_ring and cap as .step or .stl, by selecting each body in the model tree, and clicking “File > Export”.
5. Import file(s) into your slicer. I would recommend printing them separately because of quite different settings.
6. The cap is printed face down and needs some small supports. Organic supports work very well.
   
7. The spring_ring actually has a thread, instead of just some ribs that claw into the thread for the filter. To get the finest threads, I'd recommend printing the threaded part of the model with a lower layer height. I've used 0.1 mm. In PrusaSlicer, you can define different layer heights for different parts of the model. Simply right-click on it in the tree and select “Height range Modifier”. OR you can simply print the whole spring with a lower layer height.
   
8. Assembly: Break away the supports, insert one “wing” of the spring into the cap, compress the spring, and thread the other wing part through the cap.

PS: Print at least the spring_ring in a material, that doesn't deform (as quickly as PLA) over time, like ASA or PETG.

PPS: .step files for 49mm and 52mm included.

PPPS: It seems that font files are not getting included in a FreeCAD file, which caused a computing error for the last pad of the cap part. Therefore, I removed the lettering on ist and reuploaded the file as parametric_lens_cap_no_numbers.FCStd. – 19.08.25