This is a simple plastic part that can be used to stack the plastic parts of Prusament spools. It's actually part of a much larger project I'm working on, but it seemed useful enough to be published on its own.

If you print this with the large circle pointing down (like it is in my 3mf file), you can print this without supports. I used Prusament PETG for the print, but any material will do.

The model has a very loose fit, which is intentional. If you want it to sit snugly in your spool, try scaling it a millimeter bigger in X and Y direction.

I included the FreeCAD file for remixing and adapting the model to your needs. All relevant parameters have been put into a spreadsheet, so it's easily editable. If you just want to change the height of the visible part between spools, it's the “Stacker clearance height” parameter you need to change.