Overview Link to section: Overview
I design printable parts in FreeCAD (computer-aided design, or CAD, software) with dimensions that are easy to change. The Fridge Cup is a small example: an open-topped holder that mounts to a steel surface with four magnets in its back.
Its width, height, wall thickness, and magnet pockets are editable parameters (values that control the model), so the design can be adapted to a different space or set of magnets.
Model dimensions Link to section: Model dimensions
The Fridge Cup exposes its dimensions through a FreeCAD VarSet (a set of named variables). The table includes fillets (rounded edges).
| Parameter | Default | What it controls |
|---|---|---|
| Length | 100 mm | Outer footprint length |
| Width | 30 mm | Outer footprint width |
| Depth | 75 mm | Cup height |
| Thickness | 3 mm | Wall thickness |
| Fillet | 5 mm | Vertical corner radius |
| MagDiameter | 6.2 mm | Magnet pocket diameter |
| MagThickness | 2 mm | Magnet pocket depth |
| MagInset | 10 mm | Pocket inset from the corners |
| Angle | 60° | Trapezoidal base angle |
The top edge uses twice the main fillet value. Changing the magnet parameters resizes the pockets in the model.
Editing the model Link to section: Editing the model
Changing dimensions Link to section: Changing dimensions
Open the .FCStd source (the editable FreeCAD file) and select the VarSet in the model tree. Adjust the dimensions there, recompute (rebuild the geometry from those values), and inspect the resulting geometry before exporting a new print file.
Checking a revision Link to section: Checking a revision
Useful checks for a revision include:
- Overall size changes independently from wall thickness.
- Magnet dimensions match the purchased components.
- Pocket placement still leaves enough material around the edges.
- Fillets remain valid after changing the footprint.
- The editable source is saved alongside the new export.
After changing dimensions, check for failed fillets, thin walls, or pockets that break through an edge.
Printing and assembly Link to section: Printing and assembly
Print orientation Link to section: Print orientation
The cup is designed to print without supports (temporary printed structures beneath overhangs), with its closed base on the build plate (the printer’s printing surface) and the opening facing upward.
Magnets and print files Link to section: Magnets and print files
Four 6 × 2 mm neodymium discs (rare-earth magnets) press into the rear pockets. The modeled pocket diameter is 6.2 mm; check the fit with your printer and magnets.
The .3mf export (a 3D-printing file) is available for slicing (preparing printer instructions), while the source remains the place to change the design.
Physical result and limitation Link to section: Physical result and limitation
The small magnets I used only just held two full-size dry-erase markers without slipping. For a heavier load, the next change would be larger or stronger magnets and resized pockets.
The CAD makes that change easy, but the revised mount still needs a load test on the intended surface.
Files and related builds Link to section: Files and related builds
The FreeCAD repository contains the source, 3MF, drawing, and license. Retain the attribution and license with redistributed versions.
Other examples of fitting printed geometry to real objects include the Catan organizers and the electric bicycle mounts. Each project has its own fit and assembly constraints.
My Everyday Prints collection adds adjustable household and workshop parts with editable Python source and a browser customizer.
My Guitar Floor Stand entry covers a one-piece stand with editable FreeCAD source, a padded guitar envelope, and structural simulation checks.
I built PrintCAD Brief to collect dimensions, geometry notes, and fit-test history into a shareable build brief, with an STL viewer for marking model changes.
FAQ
Which Fridge Cup dimensions can I change?
The FreeCAD VarSet exposes footprint, height, wall thickness, fillets, and magnet-pocket dimensions. Change the values, recompute, and inspect the geometry before exporting.
Does the Fridge Cup need print supports?
It is designed to print without supports, with its closed base on the build plate and its opening facing upward.
How much did the tested magnets hold?
The small magnets used in the build only just held two full-size dry-erase markers without slipping. A heavier load would need larger or stronger magnets, resized pockets, and a new load test.
Build photos
