A fileable A4 / A5 hole punch that you can always have with you in your binder.

Tested with punching a single A4 sheet at a time.

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Update 8 March 2026:

• Limit stops for A4 and (new!) A 5 sheets
• Can be inserted into two-hole A4 / A5 and (new!) four-hole A4 binders
• Center marker between the punch holes for centering exotic sheet formals

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(Simple manual) supports required, see picture. Use 0.2 mm layer height (or smaller) due to the precision curved punch holes and pins. 

Use 1.75 mm PLA filament as axle. Put the filament into hot water, straighten it, let it cool down and insert it through the larger trench up to the end. Then cut it about 1 mm shorter than the end of the larger axle trench, so you can lift it with a small screwdriver at the end of the larger trench in case of disassembly. 

Punch pins and punch holes as well as filament axle and axle bores should have reasonably tight tolerances while at the same time be reasonably free-moving. But if the gaps 

• between the punch pins and the punch holes and/or
• between the 1.75 mm filament axle and the axle bores
  do not match your printer's tolerances, then you may use the online Customizer (link below the main picture's left - but sometimes it does not work as expected) or my OpenSCAD sources (see instructions below) to adapt and create suitable .stl files for your printer.

As always I include the OpenSCAD source file for you to adapt and/or improve:

• Download and install OpenSCAD from https://www.openscad.org
• Launch OpenSCAD and open the enclosed OpenSCAD source file (/File/Open).
• Amend the parameters at the top of the file or even amend the code.
• Save your changes (/File/Save).
• Render the design (/Design/Render).
• Export the rendered design e.g. as a .stl file (/File/Export/Export as STL).
• Slice and print.

See my other designs at
https://www.thingiverse.com/thinger13/designs